Remove Wikimedia-specific hack in ParserOutput

Cleanup after I6a6c12a9. To be merged after appropriate caches are purged.

Change-Id: I849c4bd1fe59e582f9f16789e8b511719e2a5d06
Remove all uses of obsolete .editsection class

Cleanup after I6a6c12a9. To be merged after appropriate caches are purged.

Change-Id: I4950496e584735a3ceeb0e1c4123dfe6597f2ae1
Merge changes I4950496e,I849c4bd1

* changes:
  Remove all uses of obsolete .editsection class
  Remove Wikimedia-specific hack in ParserOutput