Blind fix for CrashTracer: [USER] 25 crashes in Safari at com.apple.WebCore: WebCore::Frame::document const + 6
        <rdar://problem/5263939>
        
        No one has managed to reproduce this but it looks like null check is needed here. There are plausible ways
        m_frame could be null for a live FrameView object.

        * page/FrameView.cpp:
        (WebCore::FrameView::needsLayout):



git-svn-id: http://svn.webkit.org/repository/webkit/trunk@23943 268f45cc-cd09-0410-ab3c-d52691b4dbfc