[xtend][validation] Fixed bogus validation for anon classes

see https://bugs.eclipse.org/bugs/show_bug.cgi?id=447125

Change-Id: Ia87869d589d4dc4dc1420df97e57a663a7f0a8ef
[builder] Don’t pass ‘null’ as progress monitor

Change-Id: Ie2b3afe55ab1777acf1e709cb086328fe856ab99
Merge changes Ie2b3afe5,Ia87869d5

* changes:
  [builder] Don’t pass ‘null’ as progress monitor
  [xtend][validation] Fixed bogus validation for anon classes