[GTK] Do not build quota files when QUOTA is disabled
https://bugs.webkit.org/show_bug.cgi?id=134101

Reviewed by Philippe Normand.

* CMakeLists.txt: Remove exception for GTK+ that is no longer
required since r170173.
* PlatformGTK.cmake: Generate GObject DOM bindings for Quota when enabled.

git-svn-id: http://svn.webkit.org/repository/webkit/trunk@170184 268f45cc-cd09-0410-ab3c-d52691b4dbfc