Restore a collectOnMainThreadOnly call that was accidentally removed in r34659. It will not
        be needed when heaps are actually per-thread, but this isn't the case yet, and collecting
        on a different thread causes crashes.

        * bindings/js/JSDOMBinding.h:
        (WebCore::DOMObject::DOMObject):



git-svn-id: http://svn.webkit.org/repository/webkit/trunk@34737 268f45cc-cd09-0410-ab3c-d52691b4dbfc