Reviewed by xenon.

        - http://bugzilla.opendarwin.org/show_bug.cgi?id=9479
          Disassociate the inspector from the frame when it detaches from its parent

        * WebInspector/WebInspector.m:
        (-[NSWindow setWebFrame:]): Added code to (de)register with the WebFrame
        the inspector is (no longer) targeting.
        (-[WebInspector _webFrameDetached:]): Added. Moved the code that was previously
        in -[inspectedWindowWillClose:] here. This is called by the WebFrame when it
        is detached from its parent.
        * WebInspector/WebInspectorInternal.h:
        * WebView/WebFrame.m:
        (-[WebFramePrivate dealloc]):
        (-[WebFrame _detachFromParent]): Added code to notify all registered inspectors
        that the WebFrame is detaching.
        (-[WebFrame _addInspector:]): Added.
        (-[WebFrame _removeInspector:]): Added.
        * WebView/WebFrameInternal.h:



git-svn-id: http://svn.webkit.org/repository/webkit/trunk@14906 268f45cc-cd09-0410-ab3c-d52691b4dbfc