[GTK] Remove comment about possibility of handling ObjCPolymorphic (it's used by ObjC bindings only)
https://bugs.webkit.org/show_bug.cgi?id=117546

Patch by Diego Pino Garcia <dpino@igalia.com> on 2013-06-18
Reviewed by Xan Lopez.

According to the WebKit IDL spec the modifier ObjCPolymorphic only
applies to the Objective-C bindings generator

* bindings/scripts/CodeGeneratorGObject.pm:
(IsPolymorphic): Remove comment. Search parameter 'type' in array, instead of
concatening a series of 'or' conditionals.

git-svn-id: http://svn.webkit.org/repository/webkit/trunk@151682 268f45cc-cd09-0410-ab3c-d52691b4dbfc