RenderLayer::scrollRectToVisible with MallocScribble enabled

        I tried to fix this earlier today but my fix caused a regression
        scrolling through RSS pages. It turns out that sometimes scroll
        events need to propagate immediately, and sometimes they must be
        delayed or they risk deleting objects that are expected to be
        around after the event has propagated. Mitz's original fix made
        sheduleEvent() only delay events that happen during layout. This
        fix marks two other places in addition to layout where events also
        need to be delayed. These two places are places that were marked
        with FIXMEs that Mitz removed in his original patch. (There was a
        third FIXME in RenderLayer::updateScrollInfoAfterLayout() but that
        case is only called through layout and is covered by Mitz's
        original patch.)

        * page/FrameView.cpp:
        (WebCore::FrameView::~FrameView): Added assertion.
        (WebCore::FrameView::layout): Call new functions to increment and 
        decrement the queued events count.
        (WebCore::FrameView::pauseScheduledEvents):
        (WebCore::FrameView::resumeScheduledEvents): Decrement queued 
        events count and dispatch events if the count has zeroed.
        * page/FrameView.h:
        * rendering/RenderLayer.cpp:
        (WebCore::RenderLayer::scrollRectToVisible):
        (WebCore::Marquee::start):


git-svn-id: http://svn.webkit.org/repository/webkit/trunk@20360 268f45cc-cd09-0410-ab3c-d52691b4dbfc