Fix by Darin, reviewed by me.

        Fix for <rdar://problem/5171145> Safari crashed closing tab in NSInputContext updateInputContexts

        * platform/mac/WidgetMac.mm:
        (WebCore::safeRemoveFromSuperview): Added. If the view is the window's first responder, then 
         set the window's first responder to nil so we don't leave the window pointing to a view that's no longer in it.
        (WebCore::Widget::setFocus): Don't attempt to focus the view if it has no window.
        (WebCore::Widget::removeFromSuperview): Call safeRemoveFromSuperview.
        (WebCore::Widget::afterMouseDown): ditto.

WebKit:

        Fix by Darin, reviewed by me.

        Fix for <rdar://problem/5171145> Safari crashed closing tab in NSInputContext updateInputContexts

        * WebView/WebFrameView.mm: (-[WebFrameView _setDocumentView:]): If the old view is the first responder,
        then set the window's first responder to nil so we don't leave the window pointing to a view that's no longer in it.



git-svn-id: http://svn.webkit.org/repository/webkit/trunk@21632 268f45cc-cd09-0410-ab3c-d52691b4dbfc