Yet anther JSC build fix after r143304.

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



git-svn-id: http://svn.webkit.org/repository/webkit/trunk@143309 268f45cc-cd09-0410-ab3c-d52691b4dbfc
[chromium] fix ScrollAnimatorNoneTest after r143295
https://bugs.webkit.org/show_bug.cgi?id=110189

Reviewed by Nico Weber.

* tests/ScrollAnimatorNoneTest.cpp:
(MockScrollableArea):


git-svn-id: http://svn.webkit.org/repository/webkit/trunk@143310 268f45cc-cd09-0410-ab3c-d52691b4dbfc