Reviewed by Kenneth Rohde Christiansen.

        [Qt] tests/hybridPixmap fails
        https://bugs.webkit.org/show_bug.cgi?id=37316

        The problem was that JSC::Instance::createRuntimeObject was never called.
        This is fixed by overloading newRuntimeObject and calling Instance::createRuntimeObject
        in between, instead of creating the runtime object directly inside the static function
        QtPixmapInstance::createRuntimeObject, which had to be renamed as to not overshadow the virtual function.

        This fixes an existing test, tests/hybridPixmap

        * bridge/qt/qt_pixmapruntime.cpp:
        (JSC::Bindings::QtPixmapInstance::newRuntimeObject):
        (JSC::Bindings::QtPixmapInstance::createPixmapRuntimeObject):
        * bridge/qt/qt_pixmapruntime.h:
        * bridge/qt/qt_runtime.cpp:
        (JSC::Bindings::convertQVariantToValue):

git-svn-id: http://svn.webkit.org/repository/webkit/trunk@61089 268f45cc-cd09-0410-ab3c-d52691b4dbfc