Reviewed by Adele.

    Reviewed by Adele.

        - started factoring most of the guts of WebDataSource into a new class

        WebDocumentLoadState is decoupled from the rest of WebKit and will
        be moved down to WebCore. I only moved one of the data fields of
        WebDataSource for now.

        * Loader/WebDocumentLoadState.h: Added.
        * Loader/WebDocumentLoadState.m: Added.
        (-[WebDocumentLoadState initWithRequest:]): New class.
        (-[WebDocumentLoadState dealloc]):
        (-[WebDocumentLoadState setFrameLoader:]):
        (-[WebDocumentLoadState setMainResourceData:]):
        (-[WebDocumentLoadState mainResourceData]):
        * Loader/WebFrameLoader.m:
        (-[WebFrameLoader _setDataSource:]): Remove redundant _setWebFrame: call,
        it would have been called already by this point.
        (-[WebFrameLoader _setProvisionalDataSource:]): ditto.
        * WebKit.xcodeproj/project.pbxproj:
        * WebView/WebDataSource.m:
        (-[WebDataSourcePrivate dealloc]):
        (-[WebDataSource _setWebFrame:]):
        (-[WebDataSource _setPrimaryLoadComplete:]):
        (-[WebDataSource initWithRequest:]):
        (-[WebDataSource data]):

git-svn-id: https://svn.webkit.org/repository/webkit/trunk@16004 268f45cc-cd09-0410-ab3c-d52691b4dbfc