Reviewed by Simon Fraser.

        Update of fixed elements is not made correctly when the page has been scrolled
        https://bugs.webkit.org/show_bug.cgi?id=36783

        * fast/repaint/fixed-child-move-after-scroll.html: Added.
        * fast/repaint/fixed-child-of-fixed-move-after-scroll.html: Added.
        * fast/repaint/fixed-child-of-transformed-move-after-scroll.html: Added.
        * fast/repaint/fixed-move-after-scroll.html: Added.
        * platform/mac/fast/repaint/fixed-child-move-after-scroll-expected.checksum: Added.
        * platform/mac/fast/repaint/fixed-child-move-after-scroll-expected.png: Added.
        * platform/mac/fast/repaint/fixed-child-move-after-scroll-expected.txt: Added.
        * platform/mac/fast/repaint/fixed-child-of-fixed-move-after-scroll-expected.checksum: Added.
        * platform/mac/fast/repaint/fixed-child-of-fixed-move-after-scroll-expected.png: Added.
        * platform/mac/fast/repaint/fixed-child-of-fixed-move-after-scroll-expected.txt: Added.
        * platform/mac/fast/repaint/fixed-child-of-transformed-move-after-scroll-expected.checksum: Added.
        * platform/mac/fast/repaint/fixed-child-of-transformed-move-after-scroll-expected.png: Added.
        * platform/mac/fast/repaint/fixed-child-of-transformed-move-after-scroll-expected.txt: Added.
        * platform/mac/fast/repaint/fixed-move-after-scroll-expected.checksum: Added.
        * platform/mac/fast/repaint/fixed-move-after-scroll-expected.png: Added.
        * platform/mac/fast/repaint/fixed-move-after-scroll-expected.txt: Added.
2010-04-21  Benjamin Poulain  <ikipou@gmail.com>

        Reviewed by Simon Fraser.

        Update of fixed elements is not made correctly when the page has been scrolled
        https://bugs.webkit.org/show_bug.cgi?id=36783

        When a fixed element was updated, the old geometry was not repainted correctly
        because the repaint rect was cached during the layout and not updated when
        scrolling.

        The rect is now updated while scrolling so the region updated correspond to the
        region of the element on the screen.

        The method RenderLayer::updateRepaintRectsAfterScroll() updates
        the repaint rect of all fixed tree after scroll.

        Tests: fast/repaint/fixed-child-move-after-scroll.html
               fast/repaint/fixed-child-of-fixed-move-after-scroll.html
               fast/repaint/fixed-child-of-transformed-move-after-scroll.html
               fast/repaint/fixed-move-after-scroll.html

        * page/FrameView.cpp:
        (WebCore::FrameView::scrollPositionChanged):
        * rendering/RenderLayer.cpp:
        (WebCore::RenderLayer::updateRepaintRectsAfterScroll):
        * rendering/RenderLayer.h:

git-svn-id: http://svn.webkit.org/repository/webkit/trunk@57971 268f45cc-cd09-0410-ab3c-d52691b4dbfc