Reviewed by Adam.
WebKit:
        Migrated drag state and logic to WebCore, removed superfluous methods

        * ChangeLog:
        * WebCoreSupport/WebDragClient.h:
        * WebCoreSupport/WebDragClient.mm:
        (WebDragClient::dragSourceActionMaskForPoint):
        * WebCoreSupport/WebFrameBridge.mm:
           allowDHTMLDrag move to WebCore::EventHandler
        * WebView/WebHTMLView.mm:
        (-[WebHTMLView _startDraggingImage:at:operation:event:sourceIsDHTML:DHTMLWroteData:]):
        (-[WebHTMLView draggedImage:movedTo:]):
        (-[WebHTMLView draggedImage:endedAt:operation:]):
          dragOffset and dragSourecAction is now stored in WebCore::DragController
          migrated _delegateDragSourceActionMask to WebCore::DragController
        * WebView/WebHTMLViewInternal.h:
          Removed dragOffset declaration, migrated to WebCore::DragController
        * WebView/WebView.mm:
          removed unnecessary method, _loadingDragOperationForDraggingInfo                       

WebKitQt:       
        Reviewed by Adam.

        Stub for new DragClient method

        * WebCoreSupport/DragClientQt.cpp:
        (WebCore::DragClientQt::dragSourceActionMaskForPoint):
        * WebCoreSupport/DragClientQt.h:                  

WebCore:
        Reviewed by Adam.

        Migrated more drag logic and state to WebCore
                                              
        * page/DragClient.h:       

        * page/DragController.cpp:
        (WebCore::DragController::delegateDragSourceAction):
          New forwarding method for the UI delegate
        * page/DragController.h:
        (WebCore::DragController::dragOffset):
          Now store the drag offset -- the offset of the cursor relative to the drag image)
          in DragController
        * page/EventHandler.cpp:
        (WebCore::EventHandler::allowDHTMLDrag):
          Moved from WebFrameBridge
        * page/EventHandler.h:
        * page/mac/EventHandlerMac.mm:
        (WebCore::EventHandler::eventMayStartDrag):
        (WebCore::EventHandler::handleDrag):                  
          EventHandlerMac now uses EventHandler::allowDHTMLDrag rather than the 
          implementation in WebFrameBridge
        * page/mac/WebCoreFrameBridge.h:
          removed definition of allowDHTMLDrag from WebFrameBridge
        * platform/graphics/svg/SVGImageEmptyClients.h:
        (WebCore::SVGEmptyDragClient::dragSourceActionMaskForPoint):
          Updated empty DragClient



git-svn-id: http://svn.webkit.org/repository/webkit/trunk@19230 268f45cc-cd09-0410-ab3c-d52691b4dbfc