Verify that the plugin annotation system does not try to resolve @see and other annotations

Problem/Motivation

Add a class loader like this:

spl_autoload_register( function ($class_name) {
  file_put_contents(__DIR__ . '/classes.txt', $class_name . "\n", FILE_APPEND);
  },
  FALSE, TRUE);

It generates a classes.txt file.

Look at that file like this:

sort classes.txt | uniq -c

You'll see stuff like this:

   2 Drupal\Core\Annotation\PluginID
   3 Drupal\Core\Annotation\Translation
   5 Drupal\Core\Annotation\code
   3 Drupal\Core\Annotation\end
   3 Drupal\Core\Annotation\end_code
   5 Drupal\Core\Annotation\endcode
  25 Drupal\Core\Annotation\ingroup
   1 Drupal\Core\Annotation\property
  11 Drupal\Core\Annotation\see
   2 Drupal\Core\Annotation\todo

This means that the classloader is being asked to autoload, for instance, Drupal\Core\Annotation\ingroup 25 times in a front page load.

That's because the annotation system isn't filtering out known-bad annotations.

At absolute best this means that the autoloader has to waste time dealing with this stuff, and at worst has to do a file_exists() for each of these requests.

Proposed resolution

Have the annotation system filter out known annotations.

Remaining tasks

User interface changes

API changes

Data model changes