Reviewed by Darin, landed by ap.

    Reviewed by Darin, landed by ap.

        - fix http://bugzilla.opendarwin.org/show_bug.cgi?id=9316
          REGRESSION: text field width shrinks on first keystroke

        Test: fast/forms/floating-textfield-relayout.html

        * page/FrameView.cpp:
        (WebCore::FrameView::layoutRoot): Added. During subtree relayout, returns
        the subtree root. Otherwise returns 0.
        (WebCore::FrameView::layoutPending): Made const.
        * page/FrameView.h:
        * rendering/RenderBox.cpp:
        (WebCore::RenderBox::calcWidth): Added early return if this is the root
        of a subtree being laid out.

git-svn-id: https://svn.webkit.org/repository/webkit/trunk@15013 268f45cc-cd09-0410-ab3c-d52691b4dbfc