- pull a bit of WebDataSource code into WebFrameLoader

        * Loader/WebFrameLoader.m:
        (-[WebFrameLoader _receivedError:]):
        (-[WebFrameLoader webFrame]):
        (-[WebFrameLoader _handleFallbackContent]):
        (+[WebFrameLoader _canShowMIMEType:]):
        (+[WebFrameLoader _representationExistsForURLScheme:]):
        (+[WebFrameLoader _generatedMIMETypeForURLScheme:]):
        * WebView/WebDataSource.m:
        * WebView/WebDataSourceInternal.h:



git-svn-id: http://svn.webkit.org/repository/webkit/trunk@15947 268f45cc-cd09-0410-ab3c-d52691b4dbfc