Bug 1000875 - Give nsDOMWindowUtils::CheckAndClearPaintedState the ability to check paints of canvas frames. r=roc

dom/base/nsDOMWindowUtils.cpp

@@ -3076,6 +3076,17 @@ nsDOMWindowUtils::CheckAndClearPaintedState(nsIDOMElement* aElement, bool* aResu
     return NS_OK;
   }
 
+  // Get the outermost frame for the content node, so that we can test
+  // canvasframe invalidations by observing the documentElement.
+  for (;;) {
+    nsIFrame* parentFrame = frame->GetParent();
+    if (parentFrame && parentFrame->GetContent() == content) {
+      frame = parentFrame;
+    } else {
+      break;
+    }
+  }
+
   *aResult = frame->CheckAndClearPaintedState();
   return NS_OK;
 }