diff --git a/core/package.json b/core/package.json
index a736329180..82d6b0c649 100644
--- a/core/package.json
+++ b/core/package.json
@@ -5,13 +5,14 @@
   "private": true,
   "scripts": {
     "build:js": "node ./scripts/js/babel-es6-build.js",
-    "watch:js": "node ./scripts/js/babel-es6-watch.js",
+    "watch:js": "cross-env NODE_ENV=development node ./scripts/js/babel-es6-watch.js",
     "lint:core-js": "node ./node_modules/eslint/bin/eslint.js --ext=.es6.js . --fix || exit 0"
   },
   "devDependencies": {
     "babel-core": "6.24.1",
-    "babel-preset-es2015": "6.16.0",
+    "babel-preset-env": "1.4.0",
     "chokidar": "1.6.1",
+    "cross-env": "^4.0.0",
     "eslint": "3.19.0",
     "eslint-config-airbnb": "14.1.0",
     "eslint-plugin-import": "2.2.0",
@@ -21,7 +22,18 @@
   },
   "babel": {
     "presets": [
-      "es2015"
+      [
+        "env",
+        {
+          "modules": false,
+          "targets": {
+            "browsers": [
+              "last 2 versions",
+              "ie >= 9"
+            ]
+          }
+        }
+      ]
     ]
   }
 }
diff --git a/core/scripts/js/babel-es6-build.js b/core/scripts/js/babel-es6-build.js
index e073f6a431..0178d44ec5 100644
--- a/core/scripts/js/babel-es6-build.js
+++ b/core/scripts/js/babel-es6-build.js
@@ -11,44 +11,32 @@
 
 const fs = require('fs');
 const path = require('path');
-const babel = require('babel-core');
 const glob = require('glob');
 
-// Logging human-readable timestamp.
-const log = function (message) {
-  // eslint-disable-next-line no-console
-  console.log(`[${new Date().toTimeString().slice(0, 8)}] ${message}`);
-};
-
-function addSourceMappingUrl(code, loc) {
-  return code + '\n\n//# sourceMappingURL=' + path.basename(loc);
-}
-
-const changedOrAdded = (filePath) => {
-  babel.transformFile(filePath, {
-    sourceMaps: true,
-    comments: false
-  }, function (err, result) {
-    const fileName = filePath.slice(0, -7);
-    // we've requested for a sourcemap to be written to disk
-    let mapLoc = `${fileName}.js.map`;
-
-    fs.writeFile(mapLoc, JSON.stringify(result.map));
-    fs.writeFile(`${fileName}.js`, addSourceMappingUrl(result.code, mapLoc));
-
-    log(`'${filePath}' is being processed.`);
-  });
-};
+const changeOrAdded = require('./changeOrAdded');
+const log = require('./log');
 
+// Match only on .es6.js files.
 const fileMatch = './**/*.es6.js';
+// Ignore everything in node_modules
 const globOptions = {
-  ignore: 'node_modules/**'
+  ignore: './node_modules/**'
 };
 const processFiles = (error, filePaths) => {
   if (error) {
     process.exitCode = 1;
   }
-  filePaths.forEach(changedOrAdded);
+  // Process all the found files.
+  filePaths.forEach(changeOrAdded);
 };
-glob(fileMatch, globOptions, processFiles);
+
+// Run build:js with some special arguments to only parse specific files.
+// npm run build:js -- --files misc/drupal.es6.js misc/drupal.init.es6.js
+// Only misc/drupal.es6.js misc/drupal.init.es6.js will be processed.
+if (process.argv.length > 2 && process.argv[2] === '--files') {
+  processFiles(null, process.argv.splice(3, process.argv.length));
+}
+else {
+  glob(fileMatch, globOptions, processFiles);
+}
 process.exitCode = 0;
diff --git a/core/scripts/js/babel-es6-watch.js b/core/scripts/js/babel-es6-watch.js
index d614774f29..9b49482236 100644
--- a/core/scripts/js/babel-es6-watch.js
+++ b/core/scripts/js/babel-es6-watch.js
@@ -11,50 +11,29 @@
 
 const fs = require('fs');
 const path = require('path');
-const babel = require('babel-core');
 const chokidar = require('chokidar');
 
-// Logging human-readable timestamp.
-const log = function log(message) {
-  // eslint-disable-next-line no-console
-  console.log(`[${new Date().toTimeString().slice(0, 8)}] ${message}`);
-};
-
-function addSourceMappingUrl(code, loc) {
-  return `${code}\n\n//# sourceMappingURL=${path.basename(loc)}`;
-}
+const changeOrAdded = require('./changeOrAdded');
+const log = require('./log');
 
+// Match only on .es6.js files.
 const fileMatch = './**/*.es6.js';
+// Ignore everything in node_modules
 const watcher = chokidar.watch(fileMatch, {
   ignoreInitial: true,
-  ignored: 'node_modules/**'
+  ignored: './node_modules/**'
 });
 
-const changedOrAdded = (filePath) => {
-  babel.transformFile(filePath, {
-    sourceMaps: true,
-    comments: false
-  }, (err, result) => {
-    const fileName = filePath.slice(0, -7);
-    // we've requested for a sourcemap to be written to disk
-    const mapLoc = `${fileName}.js.map`;
-
-    fs.writeFileSync(mapLoc, JSON.stringify(result.map));
-    fs.writeFileSync(`${fileName}.js`, addSourceMappingUrl(result.code, mapLoc));
-
-    log(`'${filePath}' has been changed.`);
-  });
-};
-
 const unlinkHandler = (err) => {
   if (err) {
     log(err);
   }
 };
 
+// Watch for filesystem changes.
 watcher
-  .on('add', filePath => changedOrAdded(filePath))
-  .on('change', filePath => changedOrAdded(filePath))
+  .on('add', changeOrAdded)
+  .on('change', changeOrAdded)
   .on('unlink', (filePath) => {
     const fileName = filePath.slice(0, -7);
     fs.stat(`${fileName}.js`, () => {
diff --git a/core/scripts/js/changeOrAdded.js b/core/scripts/js/changeOrAdded.js
new file mode 100644
index 0000000000..5cdbe0d276
--- /dev/null
+++ b/core/scripts/js/changeOrAdded.js
@@ -0,0 +1,25 @@
+const fs = require('fs');
+const babel = require('babel-core');
+
+const log = require('./log');
+
+module.exports = (filePath) => {
+  const moduleName = filePath.slice(0, -7);
+  log(`'${filePath}' is being processed.`);
+  // Transform the file.
+  // Check process.env.NODE_ENV to see if we should create sourcemaps.
+  babel.transformFile(
+    filePath,
+    {
+      sourceMaps: process.env.NODE_ENV === 'development' ? 'inline' : false,
+      comments: false
+    },
+    (err, result) => {
+      const fileName = filePath.slice(0, -7);
+      // Write the result to the filesystem.
+      fs.writeFile(`${fileName}.js`, result.code, () => {
+        log(`'${filePath}' is finished.`);
+      });
+    }
+  );
+}
diff --git a/core/scripts/js/log.js b/core/scripts/js/log.js
new file mode 100644
index 0000000000..08349b3ae3
--- /dev/null
+++ b/core/scripts/js/log.js
@@ -0,0 +1,4 @@
+module.exports = (message) => {
+  // Logging human-readable timestamp.
+  console.log(`[${new Date().toTimeString().slice(0, 8)}] ${message}`);
+}
diff --git a/core/yarn.lock b/core/yarn.lock
index 5c73ea85ea..0bea444cee 100644
--- a/core/yarn.lock
+++ b/core/yarn.lock
@@ -185,6 +185,14 @@ babel-generator@^6.24.1:
     source-map "^0.5.0"
     trim-right "^1.0.1"
 
+babel-helper-builder-binary-assignment-operator-visitor@^6.24.1:
+  version "6.24.1"
+  resolved "https://registry.yarnpkg.com/babel-helper-builder-binary-assignment-operator-visitor/-/babel-helper-builder-binary-assignment-operator-visitor-6.24.1.tgz#cce4517ada356f4220bcae8a02c2b346f9a56664"
+  dependencies:
+    babel-helper-explode-assignable-expression "^6.24.1"
+    babel-runtime "^6.22.0"
+    babel-types "^6.24.1"
+
 babel-helper-call-delegate@^6.24.1:
   version "6.24.1"
   resolved "https://registry.yarnpkg.com/babel-helper-call-delegate/-/babel-helper-call-delegate-6.24.1.tgz#ece6aacddc76e41c3461f88bfc575bd0daa2df8d"
@@ -203,6 +211,14 @@ babel-helper-define-map@^6.24.1:
     babel-types "^6.24.1"
     lodash "^4.2.0"
 
+babel-helper-explode-assignable-expression@^6.24.1:
+  version "6.24.1"
+  resolved "https://registry.yarnpkg.com/babel-helper-explode-assignable-expression/-/babel-helper-explode-assignable-expression-6.24.1.tgz#f25b82cf7dc10433c55f70592d5746400ac22caa"
+  dependencies:
+    babel-runtime "^6.22.0"
+    babel-traverse "^6.24.1"
+    babel-types "^6.24.1"
+
 babel-helper-function-name@^6.24.1:
   version "6.24.1"
   resolved "https://registry.yarnpkg.com/babel-helper-function-name/-/babel-helper-function-name-6.24.1.tgz#d3475b8c03ed98242a25b48351ab18399d3580a9"
@@ -242,6 +258,16 @@ babel-helper-regex@^6.24.1:
     babel-types "^6.24.1"
     lodash "^4.2.0"
 
+babel-helper-remap-async-to-generator@^6.24.1:
+  version "6.24.1"
+  resolved "https://registry.yarnpkg.com/babel-helper-remap-async-to-generator/-/babel-helper-remap-async-to-generator-6.24.1.tgz#5ec581827ad723fecdd381f1c928390676e4551b"
+  dependencies:
+    babel-helper-function-name "^6.24.1"
+    babel-runtime "^6.22.0"
+    babel-template "^6.24.1"
+    babel-traverse "^6.24.1"
+    babel-types "^6.24.1"
+
 babel-helper-replace-supers@^6.24.1:
   version "6.24.1"
   resolved "https://registry.yarnpkg.com/babel-helper-replace-supers/-/babel-helper-replace-supers-6.24.1.tgz#bf6dbfe43938d17369a213ca8a8bf74b6a90ab1a"
@@ -266,25 +292,45 @@ babel-messages@^6.23.0:
   dependencies:
     babel-runtime "^6.22.0"
 
-babel-plugin-check-es2015-constants@^6.3.13:
+babel-plugin-check-es2015-constants@^6.22.0:
   version "6.22.0"
   resolved "https://registry.yarnpkg.com/babel-plugin-check-es2015-constants/-/babel-plugin-check-es2015-constants-6.22.0.tgz#35157b101426fd2ffd3da3f75c7d1e91835bbf8a"
   dependencies:
     babel-runtime "^6.22.0"
 
-babel-plugin-transform-es2015-arrow-functions@^6.3.13:
+babel-plugin-syntax-async-functions@^6.8.0:
+  version "6.13.0"
+  resolved "https://registry.yarnpkg.com/babel-plugin-syntax-async-functions/-/babel-plugin-syntax-async-functions-6.13.0.tgz#cad9cad1191b5ad634bf30ae0872391e0647be95"
+
+babel-plugin-syntax-exponentiation-operator@^6.8.0:
+  version "6.13.0"
+  resolved "https://registry.yarnpkg.com/babel-plugin-syntax-exponentiation-operator/-/babel-plugin-syntax-exponentiation-operator-6.13.0.tgz#9ee7e8337290da95288201a6a57f4170317830de"
+
+babel-plugin-syntax-trailing-function-commas@^6.22.0:
+  version "6.22.0"
+  resolved "https://registry.yarnpkg.com/babel-plugin-syntax-trailing-function-commas/-/babel-plugin-syntax-trailing-function-commas-6.22.0.tgz#ba0360937f8d06e40180a43fe0d5616fff532cf3"
+
+babel-plugin-transform-async-to-generator@^6.22.0:
+  version "6.24.1"
+  resolved "https://registry.yarnpkg.com/babel-plugin-transform-async-to-generator/-/babel-plugin-transform-async-to-generator-6.24.1.tgz#6536e378aff6cb1d5517ac0e40eb3e9fc8d08761"
+  dependencies:
+    babel-helper-remap-async-to-generator "^6.24.1"
+    babel-plugin-syntax-async-functions "^6.8.0"
+    babel-runtime "^6.22.0"
+
+babel-plugin-transform-es2015-arrow-functions@^6.22.0:
   version "6.22.0"
   resolved "https://registry.yarnpkg.com/babel-plugin-transform-es2015-arrow-functions/-/babel-plugin-transform-es2015-arrow-functions-6.22.0.tgz#452692cb711d5f79dc7f85e440ce41b9f244d221"
   dependencies:
     babel-runtime "^6.22.0"
 
-babel-plugin-transform-es2015-block-scoped-functions@^6.3.13:
+babel-plugin-transform-es2015-block-scoped-functions@^6.22.0:
   version "6.22.0"
   resolved "https://registry.yarnpkg.com/babel-plugin-transform-es2015-block-scoped-functions/-/babel-plugin-transform-es2015-block-scoped-functions-6.22.0.tgz#bbc51b49f964d70cb8d8e0b94e820246ce3a6141"
   dependencies:
     babel-runtime "^6.22.0"
 
-babel-plugin-transform-es2015-block-scoping@^6.14.0:
+babel-plugin-transform-es2015-block-scoping@^6.23.0:
   version "6.24.1"
   resolved "https://registry.yarnpkg.com/babel-plugin-transform-es2015-block-scoping/-/babel-plugin-transform-es2015-block-scoping-6.24.1.tgz#76c295dc3a4741b1665adfd3167215dcff32a576"
   dependencies:
@@ -294,7 +340,7 @@ babel-plugin-transform-es2015-block-scoping@^6.14.0:
     babel-types "^6.24.1"
     lodash "^4.2.0"
 
-babel-plugin-transform-es2015-classes@^6.14.0:
+babel-plugin-transform-es2015-classes@^6.23.0:
   version "6.24.1"
   resolved "https://registry.yarnpkg.com/babel-plugin-transform-es2015-classes/-/babel-plugin-transform-es2015-classes-6.24.1.tgz#5a4c58a50c9c9461e564b4b2a3bfabc97a2584db"
   dependencies:
@@ -308,33 +354,33 @@ babel-plugin-transform-es2015-classes@^6.14.0:
     babel-traverse "^6.24.1"
     babel-types "^6.24.1"
 
-babel-plugin-transform-es2015-computed-properties@^6.3.13:
+babel-plugin-transform-es2015-computed-properties@^6.22.0:
   version "6.24.1"
   resolved "https://registry.yarnpkg.com/babel-plugin-transform-es2015-computed-properties/-/babel-plugin-transform-es2015-computed-properties-6.24.1.tgz#6fe2a8d16895d5634f4cd999b6d3480a308159b3"
   dependencies:
     babel-runtime "^6.22.0"
     babel-template "^6.24.1"
 
-babel-plugin-transform-es2015-destructuring@^6.16.0:
+babel-plugin-transform-es2015-destructuring@^6.23.0:
   version "6.23.0"
   resolved "https://registry.yarnpkg.com/babel-plugin-transform-es2015-destructuring/-/babel-plugin-transform-es2015-destructuring-6.23.0.tgz#997bb1f1ab967f682d2b0876fe358d60e765c56d"
   dependencies:
     babel-runtime "^6.22.0"
 
-babel-plugin-transform-es2015-duplicate-keys@^6.6.0:
+babel-plugin-transform-es2015-duplicate-keys@^6.22.0:
   version "6.24.1"
   resolved "https://registry.yarnpkg.com/babel-plugin-transform-es2015-duplicate-keys/-/babel-plugin-transform-es2015-duplicate-keys-6.24.1.tgz#73eb3d310ca969e3ef9ec91c53741a6f1576423e"
   dependencies:
     babel-runtime "^6.22.0"
     babel-types "^6.24.1"
 
-babel-plugin-transform-es2015-for-of@^6.6.0:
+babel-plugin-transform-es2015-for-of@^6.23.0:
   version "6.23.0"
   resolved "https://registry.yarnpkg.com/babel-plugin-transform-es2015-for-of/-/babel-plugin-transform-es2015-for-of-6.23.0.tgz#f47c95b2b613df1d3ecc2fdb7573623c75248691"
   dependencies:
     babel-runtime "^6.22.0"
 
-babel-plugin-transform-es2015-function-name@^6.9.0:
+babel-plugin-transform-es2015-function-name@^6.22.0:
   version "6.24.1"
   resolved "https://registry.yarnpkg.com/babel-plugin-transform-es2015-function-name/-/babel-plugin-transform-es2015-function-name-6.24.1.tgz#834c89853bc36b1af0f3a4c5dbaa94fd8eacaa8b"
   dependencies:
@@ -342,13 +388,13 @@ babel-plugin-transform-es2015-function-name@^6.9.0:
     babel-runtime "^6.22.0"
     babel-types "^6.24.1"
 
-babel-plugin-transform-es2015-literals@^6.3.13:
+babel-plugin-transform-es2015-literals@^6.22.0:
   version "6.22.0"
   resolved "https://registry.yarnpkg.com/babel-plugin-transform-es2015-literals/-/babel-plugin-transform-es2015-literals-6.22.0.tgz#4f54a02d6cd66cf915280019a31d31925377ca2e"
   dependencies:
     babel-runtime "^6.22.0"
 
-babel-plugin-transform-es2015-modules-amd@^6.24.1, babel-plugin-transform-es2015-modules-amd@^6.8.0:
+babel-plugin-transform-es2015-modules-amd@^6.22.0, babel-plugin-transform-es2015-modules-amd@^6.24.1:
   version "6.24.1"
   resolved "https://registry.yarnpkg.com/babel-plugin-transform-es2015-modules-amd/-/babel-plugin-transform-es2015-modules-amd-6.24.1.tgz#3b3e54017239842d6d19c3011c4bd2f00a00d154"
   dependencies:
@@ -356,7 +402,7 @@ babel-plugin-transform-es2015-modules-amd@^6.24.1, babel-plugin-transform-es2015
     babel-runtime "^6.22.0"
     babel-template "^6.24.1"
 
-babel-plugin-transform-es2015-modules-commonjs@^6.16.0, babel-plugin-transform-es2015-modules-commonjs@^6.24.1:
+babel-plugin-transform-es2015-modules-commonjs@^6.23.0, babel-plugin-transform-es2015-modules-commonjs@^6.24.1:
   version "6.24.1"
   resolved "https://registry.yarnpkg.com/babel-plugin-transform-es2015-modules-commonjs/-/babel-plugin-transform-es2015-modules-commonjs-6.24.1.tgz#d3e310b40ef664a36622200097c6d440298f2bfe"
   dependencies:
@@ -365,7 +411,7 @@ babel-plugin-transform-es2015-modules-commonjs@^6.16.0, babel-plugin-transform-e
     babel-template "^6.24.1"
     babel-types "^6.24.1"
 
-babel-plugin-transform-es2015-modules-systemjs@^6.14.0:
+babel-plugin-transform-es2015-modules-systemjs@^6.23.0:
   version "6.24.1"
   resolved "https://registry.yarnpkg.com/babel-plugin-transform-es2015-modules-systemjs/-/babel-plugin-transform-es2015-modules-systemjs-6.24.1.tgz#ff89a142b9119a906195f5f106ecf305d9407d23"
   dependencies:
@@ -373,7 +419,7 @@ babel-plugin-transform-es2015-modules-systemjs@^6.14.0:
     babel-runtime "^6.22.0"
     babel-template "^6.24.1"
 
-babel-plugin-transform-es2015-modules-umd@^6.12.0:
+babel-plugin-transform-es2015-modules-umd@^6.23.0:
   version "6.24.1"
   resolved "https://registry.yarnpkg.com/babel-plugin-transform-es2015-modules-umd/-/babel-plugin-transform-es2015-modules-umd-6.24.1.tgz#ac997e6285cd18ed6176adb607d602344ad38468"
   dependencies:
@@ -381,14 +427,14 @@ babel-plugin-transform-es2015-modules-umd@^6.12.0:
     babel-runtime "^6.22.0"
     babel-template "^6.24.1"
 
-babel-plugin-transform-es2015-object-super@^6.3.13:
+babel-plugin-transform-es2015-object-super@^6.22.0:
   version "6.24.1"
   resolved "https://registry.yarnpkg.com/babel-plugin-transform-es2015-object-super/-/babel-plugin-transform-es2015-object-super-6.24.1.tgz#24cef69ae21cb83a7f8603dad021f572eb278f8d"
   dependencies:
     babel-helper-replace-supers "^6.24.1"
     babel-runtime "^6.22.0"
 
-babel-plugin-transform-es2015-parameters@^6.16.0:
+babel-plugin-transform-es2015-parameters@^6.23.0:
   version "6.24.1"
   resolved "https://registry.yarnpkg.com/babel-plugin-transform-es2015-parameters/-/babel-plugin-transform-es2015-parameters-6.24.1.tgz#57ac351ab49caf14a97cd13b09f66fdf0a625f2b"
   dependencies:
@@ -399,20 +445,20 @@ babel-plugin-transform-es2015-parameters@^6.16.0:
     babel-traverse "^6.24.1"
     babel-types "^6.24.1"
 
-babel-plugin-transform-es2015-shorthand-properties@^6.3.13:
+babel-plugin-transform-es2015-shorthand-properties@^6.22.0:
   version "6.24.1"
   resolved "https://registry.yarnpkg.com/babel-plugin-transform-es2015-shorthand-properties/-/babel-plugin-transform-es2015-shorthand-properties-6.24.1.tgz#24f875d6721c87661bbd99a4622e51f14de38aa0"
   dependencies:
     babel-runtime "^6.22.0"
     babel-types "^6.24.1"
 
-babel-plugin-transform-es2015-spread@^6.3.13:
+babel-plugin-transform-es2015-spread@^6.22.0:
   version "6.22.0"
   resolved "https://registry.yarnpkg.com/babel-plugin-transform-es2015-spread/-/babel-plugin-transform-es2015-spread-6.22.0.tgz#d6d68a99f89aedc4536c81a542e8dd9f1746f8d1"
   dependencies:
     babel-runtime "^6.22.0"
 
-babel-plugin-transform-es2015-sticky-regex@^6.3.13:
+babel-plugin-transform-es2015-sticky-regex@^6.22.0:
   version "6.24.1"
   resolved "https://registry.yarnpkg.com/babel-plugin-transform-es2015-sticky-regex/-/babel-plugin-transform-es2015-sticky-regex-6.24.1.tgz#00c1cdb1aca71112cdf0cf6126c2ed6b457ccdbc"
   dependencies:
@@ -420,19 +466,19 @@ babel-plugin-transform-es2015-sticky-regex@^6.3.13:
     babel-runtime "^6.22.0"
     babel-types "^6.24.1"
 
-babel-plugin-transform-es2015-template-literals@^6.6.0:
+babel-plugin-transform-es2015-template-literals@^6.22.0:
   version "6.22.0"
   resolved "https://registry.yarnpkg.com/babel-plugin-transform-es2015-template-literals/-/babel-plugin-transform-es2015-template-literals-6.22.0.tgz#a84b3450f7e9f8f1f6839d6d687da84bb1236d8d"
   dependencies:
     babel-runtime "^6.22.0"
 
-babel-plugin-transform-es2015-typeof-symbol@^6.6.0:
+babel-plugin-transform-es2015-typeof-symbol@^6.23.0:
   version "6.23.0"
   resolved "https://registry.yarnpkg.com/babel-plugin-transform-es2015-typeof-symbol/-/babel-plugin-transform-es2015-typeof-symbol-6.23.0.tgz#dec09f1cddff94b52ac73d505c84df59dcceb372"
   dependencies:
     babel-runtime "^6.22.0"
 
-babel-plugin-transform-es2015-unicode-regex@^6.3.13:
+babel-plugin-transform-es2015-unicode-regex@^6.22.0:
   version "6.24.1"
   resolved "https://registry.yarnpkg.com/babel-plugin-transform-es2015-unicode-regex/-/babel-plugin-transform-es2015-unicode-regex-6.24.1.tgz#d38b12f42ea7323f729387f18a7c5ae1faeb35e9"
   dependencies:
@@ -440,7 +486,15 @@ babel-plugin-transform-es2015-unicode-regex@^6.3.13:
     babel-runtime "^6.22.0"
     regexpu-core "^2.0.0"
 
-babel-plugin-transform-regenerator@^6.16.0:
+babel-plugin-transform-exponentiation-operator@^6.22.0:
+  version "6.24.1"
+  resolved "https://registry.yarnpkg.com/babel-plugin-transform-exponentiation-operator/-/babel-plugin-transform-exponentiation-operator-6.24.1.tgz#2ab0c9c7f3098fa48907772bb813fe41e8de3a0e"
+  dependencies:
+    babel-helper-builder-binary-assignment-operator-visitor "^6.24.1"
+    babel-plugin-syntax-exponentiation-operator "^6.8.0"
+    babel-runtime "^6.22.0"
+
+babel-plugin-transform-regenerator@^6.22.0:
   version "6.24.1"
   resolved "https://registry.yarnpkg.com/babel-plugin-transform-regenerator/-/babel-plugin-transform-regenerator-6.24.1.tgz#b8da305ad43c3c99b4848e4fe4037b770d23c418"
   dependencies:
@@ -453,34 +507,39 @@ babel-plugin-transform-strict-mode@^6.24.1:
     babel-runtime "^6.22.0"
     babel-types "^6.24.1"
 
-babel-preset-es2015@6.16.0:
-  version "6.16.0"
-  resolved "https://registry.yarnpkg.com/babel-preset-es2015/-/babel-preset-es2015-6.16.0.tgz#59acecd1efbebaf48f89404840f2fe78c4d2ad5c"
-  dependencies:
-    babel-plugin-check-es2015-constants "^6.3.13"
-    babel-plugin-transform-es2015-arrow-functions "^6.3.13"
-    babel-plugin-transform-es2015-block-scoped-functions "^6.3.13"
-    babel-plugin-transform-es2015-block-scoping "^6.14.0"
-    babel-plugin-transform-es2015-classes "^6.14.0"
-    babel-plugin-transform-es2015-computed-properties "^6.3.13"
-    babel-plugin-transform-es2015-destructuring "^6.16.0"
-    babel-plugin-transform-es2015-duplicate-keys "^6.6.0"
-    babel-plugin-transform-es2015-for-of "^6.6.0"
-    babel-plugin-transform-es2015-function-name "^6.9.0"
-    babel-plugin-transform-es2015-literals "^6.3.13"
-    babel-plugin-transform-es2015-modules-amd "^6.8.0"
-    babel-plugin-transform-es2015-modules-commonjs "^6.16.0"
-    babel-plugin-transform-es2015-modules-systemjs "^6.14.0"
-    babel-plugin-transform-es2015-modules-umd "^6.12.0"
-    babel-plugin-transform-es2015-object-super "^6.3.13"
-    babel-plugin-transform-es2015-parameters "^6.16.0"
-    babel-plugin-transform-es2015-shorthand-properties "^6.3.13"
-    babel-plugin-transform-es2015-spread "^6.3.13"
-    babel-plugin-transform-es2015-sticky-regex "^6.3.13"
-    babel-plugin-transform-es2015-template-literals "^6.6.0"
-    babel-plugin-transform-es2015-typeof-symbol "^6.6.0"
-    babel-plugin-transform-es2015-unicode-regex "^6.3.13"
-    babel-plugin-transform-regenerator "^6.16.0"
+babel-preset-env@1.4.0:
+  version "1.4.0"
+  resolved "https://registry.yarnpkg.com/babel-preset-env/-/babel-preset-env-1.4.0.tgz#c8e02a3bcc7792f23cded68e0355b9d4c28f0f7a"
+  dependencies:
+    babel-plugin-check-es2015-constants "^6.22.0"
+    babel-plugin-syntax-trailing-function-commas "^6.22.0"
+    babel-plugin-transform-async-to-generator "^6.22.0"
+    babel-plugin-transform-es2015-arrow-functions "^6.22.0"
+    babel-plugin-transform-es2015-block-scoped-functions "^6.22.0"
+    babel-plugin-transform-es2015-block-scoping "^6.23.0"
+    babel-plugin-transform-es2015-classes "^6.23.0"
+    babel-plugin-transform-es2015-computed-properties "^6.22.0"
+    babel-plugin-transform-es2015-destructuring "^6.23.0"
+    babel-plugin-transform-es2015-duplicate-keys "^6.22.0"
+    babel-plugin-transform-es2015-for-of "^6.23.0"
+    babel-plugin-transform-es2015-function-name "^6.22.0"
+    babel-plugin-transform-es2015-literals "^6.22.0"
+    babel-plugin-transform-es2015-modules-amd "^6.22.0"
+    babel-plugin-transform-es2015-modules-commonjs "^6.23.0"
+    babel-plugin-transform-es2015-modules-systemjs "^6.23.0"
+    babel-plugin-transform-es2015-modules-umd "^6.23.0"
+    babel-plugin-transform-es2015-object-super "^6.22.0"
+    babel-plugin-transform-es2015-parameters "^6.23.0"
+    babel-plugin-transform-es2015-shorthand-properties "^6.22.0"
+    babel-plugin-transform-es2015-spread "^6.22.0"
+    babel-plugin-transform-es2015-sticky-regex "^6.22.0"
+    babel-plugin-transform-es2015-template-literals "^6.22.0"
+    babel-plugin-transform-es2015-typeof-symbol "^6.23.0"
+    babel-plugin-transform-es2015-unicode-regex "^6.22.0"
+    babel-plugin-transform-exponentiation-operator "^6.22.0"
+    babel-plugin-transform-regenerator "^6.22.0"
+    browserslist "^1.4.0"
+    invariant "^2.2.2"
 
 babel-register@^6.24.1:
   version "6.24.1"
@@ -579,6 +638,13 @@ braces@^1.8.2:
     preserve "^0.2.0"
     repeat-element "^1.1.2"
 
+browserslist@^1.4.0:
+  version "1.7.7"
+  resolved "https://registry.yarnpkg.com/browserslist/-/browserslist-1.7.7.tgz#0bd76704258be829b2398bb50e4b62d1a166b0b9"
+  dependencies:
+    caniuse-db "^1.0.30000639"
+    electron-to-chromium "^1.2.7"
+
 buffer-shims@~1.0.0:
   version "1.0.0"
   resolved "https://registry.yarnpkg.com/buffer-shims/-/buffer-shims-1.0.0.tgz#9978ce317388c649ad8793028c3477ef044a8b51"
@@ -597,6 +663,10 @@ callsites@^0.2.0:
   version "0.2.0"
   resolved "https://registry.yarnpkg.com/callsites/-/callsites-0.2.0.tgz#afab96262910a7f33c19a5775825c69f34e350ca"
 
+caniuse-db@^1.0.30000639:
+  version "1.0.30000664"
+  resolved "https://registry.yarnpkg.com/caniuse-db/-/caniuse-db-1.0.30000664.tgz#e16316e5fdabb9c7209b2bf0744ffc8a14201f22"
+
 caseless@~0.12.0:
   version "0.12.0"
   resolved "https://registry.yarnpkg.com/caseless/-/caseless-0.12.0.tgz#1b681c21ff84033c826543090689420d187151dc"
@@ -686,6 +756,21 @@ core-util-is@~1.0.0:
   version "1.0.2"
   resolved "https://registry.yarnpkg.com/core-util-is/-/core-util-is-1.0.2.tgz#b5fd54220aa2bc5ab57aab7140c940754503c1a7"
 
+cross-env@^4.0.0:
+  version "4.0.0"
+  resolved "https://registry.yarnpkg.com/cross-env/-/cross-env-4.0.0.tgz#16083862d08275a4628b0b243b121bedaa55dd80"
+  dependencies:
+    cross-spawn "^5.1.0"
+    is-windows "^1.0.0"
+
+cross-spawn@^5.1.0:
+  version "5.1.0"
+  resolved "https://registry.yarnpkg.com/cross-spawn/-/cross-spawn-5.1.0.tgz#e8bd0efee58fcff6f8f94510a0a554bbfa235449"
+  dependencies:
+    lru-cache "^4.0.1"
+    shebang-command "^1.2.0"
+    which "^1.2.9"
+
 cryptiles@2.x.x:
   version "2.0.5"
   resolved "https://registry.yarnpkg.com/cryptiles/-/cryptiles-2.0.5.tgz#3bdfecdc608147c1c67202fa291e7dca59eaa3b8"
@@ -781,6 +866,10 @@ ecc-jsbn@~0.1.1:
   dependencies:
     jsbn "~0.1.0"
 
+electron-to-chromium@^1.2.7:
+  version "1.3.8"
+  resolved "https://registry.yarnpkg.com/electron-to-chromium/-/electron-to-chromium-1.3.8.tgz#b2c8a2c79bb89fbbfd3724d9555e15095b5f5fb6"
+
 emoji-regex@^6.1.0:
   version "6.4.2"
   resolved "https://registry.yarnpkg.com/emoji-regex/-/emoji-regex-6.4.2.tgz#a30b6fee353d406d96cfb9fa765bdc82897eff6e"
@@ -1319,7 +1408,7 @@ interpret@^1.0.0:
   version "1.0.3"
   resolved "https://registry.yarnpkg.com/interpret/-/interpret-1.0.3.tgz#cbc35c62eeee73f19ab7b10a801511401afc0f90"
 
-invariant@^2.2.0:
+invariant@^2.2.0, invariant@^2.2.2:
   version "2.2.2"
   resolved "https://registry.yarnpkg.com/invariant/-/invariant-2.2.2.tgz#9e1f56ac0acdb6bf303306f338be3b204ae60360"
   dependencies:
@@ -1446,10 +1535,18 @@ is-typedarray@~1.0.0:
   version "1.0.0"
   resolved "https://registry.yarnpkg.com/is-typedarray/-/is-typedarray-1.0.0.tgz#e479c80858df0c1b11ddda6940f96011fcda4a9a"
 
+is-windows@^1.0.0:
+  version "1.0.1"
+  resolved "https://registry.yarnpkg.com/is-windows/-/is-windows-1.0.1.tgz#310db70f742d259a16a369202b51af84233310d9"
+
 isarray@1.0.0, isarray@^1.0.0, isarray@~1.0.0:
   version "1.0.0"
   resolved "https://registry.yarnpkg.com/isarray/-/isarray-1.0.0.tgz#bb935d48582cba168c06834957a54a3e07124f11"
 
+isexe@^2.0.0:
+  version "2.0.0"
+  resolved "https://registry.yarnpkg.com/isexe/-/isexe-2.0.0.tgz#e8fbf374dc556ff8947a10dcb0572d633f2cfa10"
+
 isobject@^2.0.0:
   version "2.1.0"
   resolved "https://registry.yarnpkg.com/isobject/-/isobject-2.1.0.tgz#f065561096a3f1da2ef46272f815c840d87e0c89"
@@ -1555,6 +1652,13 @@ loose-envify@^1.0.0:
   dependencies:
     js-tokens "^3.0.0"
 
+lru-cache@^4.0.1:
+  version "4.0.2"
+  resolved "https://registry.yarnpkg.com/lru-cache/-/lru-cache-4.0.2.tgz#1d17679c069cda5d040991a09dbc2c0db377e55e"
+  dependencies:
+    pseudomap "^1.0.1"
+    yallist "^2.0.0"
+
 micromatch@^2.1.5:
   version "2.3.11"
   resolved "https://registry.yarnpkg.com/micromatch/-/micromatch-2.3.11.tgz#86677c97d1720b363431d04d0d15293bd38c1565"
@@ -1807,6 +1911,10 @@ progress@^1.1.8:
   version "1.1.8"
   resolved "https://registry.yarnpkg.com/progress/-/progress-1.1.8.tgz#e260c78f6161cdd9b0e56cc3e0a85de17c7a57be"
 
+pseudomap@^1.0.1:
+  version "1.0.2"
+  resolved "https://registry.yarnpkg.com/pseudomap/-/pseudomap-1.0.2.tgz#f052a28da70e618917ef0a8ac34c1ae5a68286b3"
+
 punycode@^1.4.1:
   version "1.4.1"
   resolved "https://registry.yarnpkg.com/punycode/-/punycode-1.4.1.tgz#c0d5a63b2718800ad8e1eb0fa5269c84dd41845e"
@@ -2008,6 +2116,16 @@ set-immediate-shim@^1.0.1:
   version "1.0.1"
   resolved "https://registry.yarnpkg.com/set-immediate-shim/-/set-immediate-shim-1.0.1.tgz#4b2b1b27eb808a9f8dcc481a58e5e56f599f3f61"
 
+shebang-command@^1.2.0:
+  version "1.2.0"
+  resolved "https://registry.yarnpkg.com/shebang-command/-/shebang-command-1.2.0.tgz#44aac65b695b03398968c39f363fee5deafdf1ea"
+  dependencies:
+    shebang-regex "^1.0.0"
+
+shebang-regex@^1.0.0:
+  version "1.0.0"
+  resolved "https://registry.yarnpkg.com/shebang-regex/-/shebang-regex-1.0.0.tgz#da42f49740c0b42db2ca9728571cb190c98efea3"
+
 shelljs@^0.7.5:
   version "0.7.7"
   resolved "https://registry.yarnpkg.com/shelljs/-/shelljs-0.7.7.tgz#b2f5c77ef97148f4b4f6e22682e10bba8667cff1"
@@ -2208,6 +2326,12 @@ verror@1.3.6:
   dependencies:
     extsprintf "1.0.2"
 
+which@^1.2.9:
+  version "1.2.14"
+  resolved "https://registry.yarnpkg.com/which/-/which-1.2.14.tgz#9a87c4378f03e827cecaf1acdf56c736c01c14e5"
+  dependencies:
+    isexe "^2.0.0"
+
 wide-align@^1.1.0:
   version "1.1.0"
   resolved "https://registry.yarnpkg.com/wide-align/-/wide-align-1.1.0.tgz#40edde802a71fea1f070da3e62dcda2e7add96ad"
@@ -2231,3 +2355,7 @@ write@^0.2.1:
 xtend@^4.0.0:
   version "4.0.1"
   resolved "https://registry.yarnpkg.com/xtend/-/xtend-4.0.1.tgz#a5c6d532be656e23db820efb943a1f04998d63af"
+
+yallist@^2.0.0:
+  version "2.1.2"
+  resolved "https://registry.yarnpkg.com/yallist/-/yallist-2.1.2.tgz#1c11f9218f076089a47dd512f93c6699a6a81d52"