<https://webkit.org/b/121004>

Reviewed by Antti Koivisto.

Remove gratuitous FrameActionScheduler class that was really only being used
to defer the occassional "overflowchanged" event until layout had finished.

* CMakeLists.txt:
* GNUmakefile.list.am:
* Target.pri:
* WebCore.vcxproj/WebCore.vcxproj:
* WebCore.vcxproj/WebCore.vcxproj.filters:
* WebCore.xcodeproj/project.pbxproj:
* page/FrameActionScheduler.cpp:
* page/FrameActionScheduler.h:

    Removed FrameActionScheduler.

* page/FrameView.h:
* page/FrameView.cpp:
(WebCore::FrameView::FrameView):
(WebCore::FrameView::~FrameView):
(WebCore::FrameView::layout):
(WebCore::FrameView::ScheduledEvent::ScheduledEvent):
(WebCore::FrameView::scheduleEvent):
(WebCore::FrameView::pauseScheduledEvents):
(WebCore::FrameView::resumeScheduledEvents):
(WebCore::FrameView::performPostLayoutTasks):
(WebCore::FrameView::updateOverflowStatus):

    Replaced it with a Vector<ScheduledEvent> and a suppression counter.
    A ScheduledEvent is just a { Node, Event } pair.


git-svn-id: http://svn.webkit.org/repository/webkit/trunk@155315 268f45cc-cd09-0410-ab3c-d52691b4dbfc