Replace mentions of url() in docs

Here is the result for the command

grep -R "url()" * | grep -v "::url()" | grep -v "_url()" | grep -v ">url()"

against branch 8.0.x

$ grep -R "url()" * | grep -v "::url()" | grep -v "_url()" | grep -v ">url()"
core/assets/vendor/backbone/backbone.js:  // to the model's `url()`. Some possible customizations could be:
core/includes/common.inc: * Prepares a 'destination' URL query parameter for use with url().
core/includes/form.inc: *   - url_options: options passed to url() when constructing redirect URLs for
core/lib/Drupal/Core/Asset/CssOptimizer.php:   * returns the stylesheet content with all url() paths corrected.
core/lib/Drupal/Core/Asset/CssOptimizer.php:    // the url() path.
core/lib/Drupal/Core/Asset/CssOptimizer.php:    // Alter all internal url() paths. Leave external paths alone. We don't need
core/lib/Drupal/Core/Asset/CssOptimizer.php:   *   url() references in CSS files, except for external or absolute ones.
core/modules/menu_link_content/src/Plugin/migrate/source/MenuLink.php:      'options' => t('A serialized array of options to be passed to the url() or l() function, such as a query string or HTML attributes.'),
core/modules/system/src/Tests/Theme/EngineTwigTest.php:    // Verify that url() has the ability to bubble cacheability metadata:
core/modules/system/system.module: *   Optional array of options to pass to url().
core/modules/system/system.module: *   Optional array of options to pass to url().
core/modules/user/templates/username.html.twig: * - link_options: Options to pass to the url() function's $options parameter if
core/tests/Drupal/Tests/Core/DrupalTest.php:   * Tests the url() method.
core/tests/Drupal/Tests/Core/Entity/EntityUrlTest.php:   * Tests the url() method.
core/themes/classy/templates/user/username.html.twig: * - link_options: Options to pass to the url() function's $options parameter if
core/themes/stable/templates/user/username.html.twig: * - link_options: Options to pass to the url() function's $options parameter if
vendor/mikey179/vfsStream/CHANGELOG.md:   * implemented issue #34: provide `url()` method on all `vfsStreamContent` instances
vendor/mikey179/vfsStream/src/main/php/org/bovigo/vfs/vfsStreamAbstractContent.php:    public function url()
vendor/mikey179/vfsStream/src/main/php/org/bovigo/vfs/vfsStreamContent.php:    public function url();

Attaching initial version of the patch, making changes about which I was confident. I made changes in the files:

core/includes/common.inc
core/includes/form.inc
core/modules/menu_link_content/src/Plugin/migrate/source/MenuLink.php
core/modules/system/system.module

I did not change any functions in the JS files or twig templates as mentioned in the issue summary.

I was particularly not sure about core/lib/Drupal/Core/Asset/CssOptimizer.php. The code

// the url() path.
    $directory = $directory == '.' ? '' : $directory .'/';

    // Alter all internal url() paths. Leave external paths alone. We don't need
    // to normalize absolute paths here because that will be done later.
    return preg_replace('/url\(\s*([\'"]?)(?![a-z]+:|\/+)([^\'")]+)([\'"]?)\s*\)/i', 'url(\1' . $directory . '\2\3)', $file);

seems to make use of the css() function. So, I thought it would be wrong to make changes in the comments unless done in the code first. Please review :)

I've fixed the first two issues mentioned by @jhodgdon, I'm not sure where to start with the twig files though.

The \Drupal\Core\Url class doesn't contain any reference to the drupal_get_destination() function so I've removed that from the comment.

Thank you @jhodgdon.
Updated patch as per #8.

Interdiff is against the patch from #7.

Hi jennifer, have added a patch for the username.html.twig files.

Made changes as per suggestions by @jhodgdon above. Thanks !

I am sorry about missing the other two instances of the same. Thanks @jhodgdon for pointing out.

link_options: Options to set on the \Drupal\Core\Url object if linking
+ *   the user's name to the user's page.

I think the word "the" can be wrapped in the previous line for the username.html.twig files.

Updated the patch

Committed 750f647 and pushed to 8.0.x, 8.1.x and 8.2.x. Thanks!

I tried to find more instances where url() was incorrect in the codebase and I could not - nice to see this cleaned up.