Remove deprecated hook_library_alter()

RTBC, thanks Laurii!

Right this was the runtime hook, let's drop it.

+++ b/core/lib/Drupal/Core/Asset/LibraryDiscovery.php
@@ -85,8 +85,6 @@ public function getLibrariesByExtension($extension) {
-        $this->moduleHandler->alter('library', $definition, $library_name);
-        $this->themeManager->alter('library', $definition, $library_name);

We can remove the module handler and theme manager from the class itself now.

Back to RTBC, changes look good.

Can we please cleanup the test to not longer create mock objects for the module handler / theme handler?

Also, since this is a normal task, let's add a beta evaluation and examine how the change fits during the Drupal 8 beta.

Back to RTBC ...

Reviewing this.

So this confused me at first, because the hook did not appear to be marked deprecated -- it just appeared to be undocumented. What actually happened is that #2392717: Remove hook_library_alter() from theme.api.php removed the documentation of the hook... but not the test coverage or the invocation. Oops! So this change is allowed during the beta.

I updated the summary to explain this. (Note that removing deprecated code is not unfrozen; that's only strings, markup, migrate, docs, etc.) I also updated the title of the change record: https://www.drupal.org/node/2391981/revisions/view/8368695/8371373

Now reviewing the patch itself. :)

Actually @dawehner has more feedback.

We can drop

  /**
   * The mocked module handler.
   *
   * @var \Drupal\Core\Extension\ModuleHandlerInterface|\PHPUnit_Framework_MockObject_MockObject
   */
  protected $moduleHandler;

  /**
   * The mocked theme manager.
   *
   * @var \Drupal\Core\Theme\ThemeManagerInterface|\PHPUnit_Framework_MockObject_MockObject
   */
  protected $themeManager;

as well in that test file.

Somewhat related #2472119: Extension installers allow extensions with duplicate names to be enabled.

Tagging

Not really a part of the criticals and performance sprint, so removing that tag. :)

Per #19, this is okay to go in since the hook was already deprecated for removal 8.0.0 and we just missed a bit of the patch previously. Committed and pushed to 8.0.x

This should have fixed the performance regression that #2050269: hook_library_info_alter() is not called for themes caused! :)

We need a quick follow-up issue to fix the comments:

+++ b/core/lib/Drupal/Core/Asset/LibraryDiscovery.php
@@ -85,8 +69,6 @@ public function getLibrariesByExtension($extension) {
         // Allow modules and themes to dynamically attach request and context
         // specific data for this library; e.g., localization.

nit - We forgot to remove this comment, which is no longer true.