Reviewed by Oliver Hunt.

        Remove obsolete code that had been left intact to support users running WebKit with older versions of Safari.

        * Misc/WebNSViewExtras.m:  Remove _web_superviewOfClass:stoppingAtClass:.
        * Misc/WebNSWindowExtras.m:  Remove _webkit_displayThrottledWindows.
        * Misc/WebSearchableTextView.m:  Remove selectionImageForcingWhiteText:.
        * WebCoreSupport/WebImageRendererFactory.m:  Update comment to mention the last version of Safari that
        requires this class.
        * WebInspector/WebInspector.mm:  Remove sharedWebInspector and update comments to mention the last version
        of Safari that calls other obsolete methods.
        * WebView/WebDocumentPrivate.h:  Remove selectionImageForcingWhiteText:.
        * WebView/WebHTMLView.mm:  Ditto.
        * WebView/WebPDFView.mm:  Ditto.
        * WebView/WebView.mm:  Update comment to mentoin the last version of Safari that requires the obsolete method.


git-svn-id: http://svn.webkit.org/repository/webkit/trunk@30660 268f45cc-cd09-0410-ab3c-d52691b4dbfc