Disallow abstract definitions from doctrine event listener registration
bug #11160 [DoctrineBridge] Abstract Doctrine Subscribers with tags (merk)

This PR was merged into the 2.3 branch.

Discussion
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[DoctrineBridge] Abstract Doctrine Subscribers with tags

| Q             | A
| ------------- | ---
| Bug fix?      | yes
| New feature?  | no
| BC breaks?    | no
| Deprecations? | no
| Tests pass?   | yes
| Fixed tickets | this one
| License       | MIT
| Doc PR        | N/A

I've hit a problem with some doctrine listeners, built by decorating an abstract definition.

I want the abstract definition to hold the tag, however because the RegisterEventListenersAndSubscribersPass runs before abstract definitions are removed, they get added as method calls to the EventManager definition, which once the abstract service is removed, we end up with a method call that breaks the container.

I don't know if this is the best approach, it might be better not to return abstract services when calling `findTaggedServiceIds` instead?

Commits
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cbcf513 Disallow abstract definitions from doctrine event listener registration
Merge branch '2.3' into 2.4

* 2.3:
  [HttpKernel] add use statement for phpdoc
  Disabled the PHPUnit self-update on Travis
  [ClassLoader] simplified phpdoc
  [ClassLoader] Add a __call() method to XcacheClassLoader
  fix some minor typos in tests
  [Yaml] fixed mapping keys containing a quoted #
  Added fixture to test parsing of hash keys ending with a space and #
  [Filesystem Component] mkdir race condition fix #11626
  [Validator] reverted permissions change on translation files
  Fixed Factory services not within the ServiceReferenceGraph.
  [CssSelector] Fix URL to SimonSapin/cssselect repo
  [Validator] Fixed wrong translation keys/messages for Collection constraint. The error messages for a missing field and an unexpected field did not match the Contraint class
  [YAML] resolve variables in inlined YAML
  Disallow abstract definitions from doctrine event listener registration

Conflicts:
	src/Symfony/Bridge/Doctrine/DependencyInjection/CompilerPass/RegisterEventListenersAndSubscribersPass.php
	src/Symfony/Bridge/Doctrine/Tests/DependencyInjection/CompilerPass/RegisterEventListenersAndSubscribersPassTest.php
	src/Symfony/Bundle/FrameworkBundle/EventListener/SessionListener.php
	src/Symfony/Component/Filesystem/Filesystem.php