Test: LayoutTests/fast/block/positioning/height-change.html

    Test: LayoutTests/fast/block/positioning/height-change.html

        Reviewed by Hyatt.

        - fix http://bugzilla.opendarwin.org/show_bug.cgi?id=6881
          Block with position:absolute bottom:0 doesn't always move when height
          of containing block changes (affects Safari RSS)

        * rendering/RenderBlock.cpp:
        (WebCore::RenderBlock::layoutBlock): Relayout positioned children if the
        block's height changed during layout.
        * rendering/render_flexbox.cpp:
        (WebCore::RenderFlexibleBox::layoutBlock): Ditto.

git-svn-id: https://svn.webkit.org/repository/webkit/trunk@12524 268f45cc-cd09-0410-ab3c-d52691b4dbfc