http://bugs.webkit.org/show_bug.cgi?id=13076
        REGRESSION: Multiple loading tabs cause assertion in WebDocumentLoaderMac::decreaseLoadCount(unsigned long)

        Store the identifier set in the document loader since identifiers are per-webview and not global.
        
        * WebView/WebDocumentLoaderMac.h:
        * WebView/WebDocumentLoaderMac.mm:
        (WebDocumentLoaderMac::WebDocumentLoaderMac):
        (WebDocumentLoaderMac::attachToFrame):
        (WebDocumentLoaderMac::increaseLoadCount):
        (WebDocumentLoaderMac::decreaseLoadCount):



git-svn-id: http://svn.webkit.org/repository/webkit/trunk@20206 268f45cc-cd09-0410-ab3c-d52691b4dbfc