Reviewed by Sam Weinig.

        Add a way for application to provide custom, full frame, views for certain MIME types.
        
        * Interfaces/IWebEmbeddedView.idl:
        Add loading related methods.
        
        * Interfaces/IWebViewPrivate.idl:
        Add new registerEmbeddedViewMIMEType method.
        
        * WebCoreSupport/EmbeddedWidget.cpp:
        (EmbeddedWidget::didReceiveResponse):
        (EmbeddedWidget::didReceiveData):
        (EmbeddedWidget::didFinishLoading):
        (EmbeddedWidget::didFail):
        Implement these and call the IEmbeddedView methods.
        
        * WebCoreSupport/EmbeddedWidget.h:
        Inherit from PluginManualLoader.
        
        * WebCoreSupport/WebFrameLoaderClient.cpp:
        (WebFrameLoaderClient::redirectDataToPlugin):
        Handle the case where the widget is an EnbeddedWidget.
        
        (WebFrameLoaderClient::shouldUsePluginDocument):
        Have this call WebView::shouldUseEmbeddedView.
        
        * WebView.cpp:
        (WebView::canShowMIMEType):
        Have this call WebView::shouldUseEmbeddedView.
        
        (WebView::registerEmbeddedViewMIMEType):
        Add the MIME type to the set.
        
        (WebView::shouldUseEmbeddedView):
        Given a MIME type, returns whether an embedded view should be used or not.



git-svn-id: http://svn.webkit.org/repository/webkit/trunk@39665 268f45cc-cd09-0410-ab3c-d52691b4dbfc