Reviewed by Darin.
        
        - <rdar://problem/4820817> Autoscroll is broken in Mail.app (message jumps around when trying to select text)

        * fast/overflow/scrollRevealButton-expected.checksum:
        * fast/overflow/scrollRevealButton-expected.png:
        * fast/overflow/scrollRevealButton-expected.txt:

WebCore:

        Reviewed by Darin.
        
        - fixed <rdar://problem/4820817> Autoscroll is broken in Mail.app (message jumps around when trying to select text)
                
        Handle scrolling external scrollviews around the webview during
        autoscroll or when scrolling into view.
        
        This should also restore performance on BenchJS test 6 lost due to Tim's partial fix.

        * page/FrameView.cpp:
        (WebCore::FrameView::scrollRectIntoViewRecursively):
        * page/FrameView.h:
        * platform/ScrollView.h:
        * platform/gdk/ScrollViewGdk.cpp:
        (WebCore::ScrollView::visibleContentRectConsideringExternalScrollers):
        (WebCore::ScrollView::scrollRectIntoViewRecursively):
        * platform/mac/ScrollViewMac.mm:
        (WebCore::ScrollView::visibleContentRect):
        (WebCore::ScrollView::visibleContentRectConsideringExternalScrollers):
        (WebCore::ScrollView::scrollRectIntoViewRecursively):
        (WebCore::ScrollView::updateContents):
        * platform/qt/ScrollViewQt.cpp:
        (WebCore::ScrollView::visibleContentRectConsideringExternalScrollers):
        (WebCore::ScrollView::scrollRectIntoViewRecursively):
        * platform/win/ScrollViewWin.cpp:
        (WebCore::ScrollView::visibleContentRectConsideringExternalScrollers):
        * platform/win/TemporaryLinkStubs.cpp:
        (WebCore::ScrollView::scrollRectIntoViewRecursively):
        * rendering/RenderLayer.cpp:
        (WebCore::RenderLayer::scrollRectToVisible):



git-svn-id: http://svn.webkit.org/repository/webkit/trunk@20565 268f45cc-cd09-0410-ab3c-d52691b4dbfc