Reviewed by Darin.

	- fixed 3130831 - HOMEPAGE: JavaScript that tries to intercept onmousedown fails, image gets dragged instead
	- fixed 3125554 - while dragging to select text in a nested frame, you can start dragging a link or image

        * kwq/KWQKHTMLPart.h:
        * kwq/KWQKHTMLPart.mm:
	(KWQKHTMLPart::KWQKHTMLPart): Initialize new mouseDownMayStartDrag
	and mouseDownMayStartSelect methods.
        (KWQKHTMLPart::khtmlMousePressEvent): Make sure a mouse down
	won't be used to start a drag or selection if the default action
	is prevented on the mouse down event.
	(KWQKHTMLPart::mouseDown): Since the default action wasn't
	prevented, decide if this might be the start of a drag or
	selection.
        (KWQKHTMLPart::khtmlMouseMoveEvent): On a drag or selection, call
	back to the bridge to handle selection or autoscrolling
	appropriately.
	* kwq/WebCoreBridge.h: Prototype new methods.

WebKit:

	Reviewed by Darin.

	- fixed 3130831 - HOMEPAGE: JavaScript that tries to intercept onmousedown fails, image gets dragged instead
	- fixed 3125554 - while dragging to select text in a nested frame, you can start dragging a link or image

        * WebCoreSupport.subproj/WebBridge.m:
        (-[WebBridge handleMouseDragged:]): New method; call through the WebHTMLView.
        (-[WebBridge mayStartDragWithMouseDown:]): Likewise.
        (-[WebBridge handleAutoscrollForMouseDragged:]): Likewise.
        * WebView.subproj/WebHTMLView.m:
        (-[WebHTMLView mouseDragged:]): Instead of doing drag handling
	here, just pass the event to WebCore.
	(-[WebHTMLView draggedImage:endedAt:operation:]): Send a fake
	mousemove event instead of sending the current event (likely a
	mouse up as if it were a mouse move).
        * WebView.subproj/WebHTMLViewPrivate.h:
        * WebView.subproj/WebHTMLViewPrivate.m:
        (-[WebHTMLViewPrivate dealloc]): Release drag element if any.
        (-[WebHTMLView _dragImageForElement:]): New method. Split out the
	code to make the special drag image for links.
	(-[WebHTMLView _handleMouseDragged:]): Move all the drag handling
	here. This method will get called only if WebCore hasn't blocked
	default drag handling.
        (-[WebHTMLView _handleAutoscrollForMouseDragged:]): Do
	autoscroll. Autoscroll is still lame, we need a timer.
        (-[WebHTMLView _mayStartDragWithMouseDown:]): Determine if the element
	is a link or image and so may be dragged; remember the drag element.


git-svn-id: http://svn.webkit.org/repository/webkit/trunk@3229 268f45cc-cd09-0410-ab3c-d52691b4dbfc