Reviewed by hyatt, landed by ap.

WebCore:
        - fix http://bugzilla.opendarwin.org/show_bug.cgi?id=6769
          REGRESSION: Incomplete repaint when a cell's extra bottom margin grows

        Test: fast/repaint/table-extra-bottom-grow.html

        * rendering/RenderBlock.cpp:
        (WebCore::RenderBlock::overflowRect): Changed to not add the top/left overflow twice and
        allow the normal overflow height to overlap with the bottom extra height.
        * rendering/RenderTableRow.cpp:
        (WebCore::RenderTableRow::layout): Removed the code that resets the extra heights.
        * rendering/RenderTableSection.cpp:
        (WebCore::RenderTableSection::layoutRows): If the top extra height changed or the
        bottom extra height increased, just repaint the entire cell.

LayoutTests:
        * fast/repaint/table-extra-bottom-grow-expected.checksum: Added.
        * fast/repaint/table-extra-bottom-grow-expected.png: Added.
        * fast/repaint/table-extra-bottom-grow-expected.txt: Added.
        * fast/repaint/table-extra-bottom-grow.html: Added.
        * fast/repaint/table-cell-moved-expected.checksum: Removed excessive painting.
        * fast/repaint/table-cell-moved-expected.png: Ditto.
        * fast/repaint/bugzilla-6278-expected.checksum: Ditto.
        * fast/repaint/bugzilla-6278-expected.png: Ditto.



git-svn-id: http://svn.webkit.org/repository/webkit/trunk@14101 268f45cc-cd09-0410-ab3c-d52691b4dbfc