Compute minimum repaint and show them in overlay

Source/core/testing/Internals.idl

 /*
  * Copyright (C) 2012 Google Inc. All rights reserved.
  * Copyright (C) 2013 Apple Inc. All rights reserved.
  *
  * Redistribution and use in source and binary forms, with or without
  * modification, are permitted provided that the following conditions
  * are met:
  *
  * 1.  Redistributions of source code must retain the above copyright
  *     notice, this list of conditions and the following disclaimer.
@@ skipping 216 matching lines @@
     // These functions both reset the tracked repaint rects. They are inteded to be used in the following order:
     //  startTrackingRepaints, repaintRectsAsText, stopTrackingRepaints.
     [RaisesException] void startTrackingRepaints(Document document);
     [RaisesException] void stopTrackingRepaints(Document document);
 
     // |node| should be Document, HTMLIFrameElement, or unspecified.
     // If |node| is an HTMLIFrameElement, it assumes node.contentDocument is
     // specified without security checks. Unspecified means this document.
     [RaisesException] void updateLayoutIgnorePendingStylesheetsAndRunPostLayoutTasks(optional Node node);
 
+    [RaisesException] void forceFullRepaint(Document document);
+
     // Returns a list of draggable/non-draggable regions in the document.
     [RaisesException] ClientRectList draggableRegions(Document document);
     [RaisesException] ClientRectList nonDraggableRegions(Document document);
 
     // Returns a string with information about the mouse cursor used at the specified client location.
     [RaisesException] DOMString getCurrentCursorInfo(Document document);
 
     [RaisesException] DOMString markerTextForListItem(Element element);
 
     [RaisesException] DOMString baseURL(Document document);
@@ skipping 26 matching lines @@
 
     DOMString textSurroundingNode(Node node, long x, long y, unsigned long maxLength);
 
     void setFocused(boolean focused);
 
     // These functions are for testing NetInfo. You must call setNetworkStateNotifierTestOnly(true)
     // before calling setNetworkConnectionInfo.
     void setNetworkStateNotifierTestOnly(boolean testOnly);
     [RaisesException] void setNetworkConnectionInfo(DOMString type);
 };