Update WYSIWYG to version 2.6

Here's a Travis build: https://travis-ci.org/panopoly/panopoly/builds/633937130

Manual testing looked good!

I've got mixed feelings on PHP 5.3 support. Our tests haven't been running on PHP 5.3 for a while anyway. And I don't know that we really want to commit to patching all contrib modules for PHP 5.3 going forward for a version of PHP that was EOL'd over 5 years ago. I'm going to commit this and we'll see if any PHP 5.3 fans come out of the woodwork. :-)

Committed!

After merging, this appears to break our tests:

https://travis-ci.org/panopoly/panopoly/builds/634477995

I'm not sure why my original test run on Travis came back green... I'm going to look into that.

Here's a new test running with this change reverted:

https://travis-ci.org/panopoly/panopoly/builds/634775305

If that passes, then we know we need to fix this one up.

Yeah, the tests with the change reverted seem to be passing.

I think the reason the tests didn't catch it the first time is because I keep forgetting to run 'robo build:drupal-org-make' to accommodate the monorepo, so I added a git pre-commit hook to the RoboFile to try and prevent me from committing without running that. :-)

Anyway, the test failure is just an alert appearing that the tests don't expect:

  ╳  unexpected alert open: {Alert text : Are you sure you want to change the text format?
  ╳  
  ╳  Changing the text format to HTML and enabling the associated editor will permanently remove content that is not allowed in both text formats.
  ╳  
  ╳  Cancel and save your changes before switching the text format to avoid losing data.}

Here's a Travis build that will hopefully be accurate this time:

https://travis-ci.org/panopoly/panopoly/jobs/634925485

I'm gonna try running this locally too.

Manual testing worked again (I wanted to redo it, just in case I was using the wrong versions locally).

Tests on Travis are failing, though, with:

When I select "HTML" from "Editor"                                                                   # Drupal\DrupalExtension\Context\MinkContext::selectOption()
    And I confirm the popup                                                                              # TestSubContext::iConfirmPopup()
      no alert open

Could be a timing thing? The test is passing for me locally.

Here's a patch that adds a short wait.

EDIT: Here's a new Travis build: https://travis-ci.org/panopoly/panopoly/builds/634948363

Alright, that didn't work! Let's try this.

EDIT: Here's a new Travis build https://travis-ci.org/panopoly/panopoly/builds/635457251

Well, that seemed to work! Committing :-)