Bug 724432 - Skip UpdateOverflow if we did Reflow. Don't propagate UpdateOverflow in ReResolveStyleContext. r=roc

layout/base/nsCSSFrameConstructor.cpp

@@ -7980,7 +7980,7 @@ nsCSSFrameConstructor::ProcessRestyledFrames(nsStyleChangeList& aChangeList)
         ApplyRenderingChangeToTree(presContext, frame, hint);
         didInvalidate = true;
       }
-      if (hint & nsChangeHint_UpdateOverflow) {
+      if ((hint & nsChangeHint_UpdateOverflow) && !didReflow) {
         while (frame) {
           frame->UpdateOverflow();
           nsIFrame* next =

layout/base/nsFrameManager.cpp

@@ -1061,6 +1061,8 @@ nsFrameManager::ReResolveStyleContext(nsPresContext     *aPresContext,
       NS_SubtractHint(aMinChange, nsChangeHint_ClearAncestorIntrinsics);
   }
 
+  aMinChange = NS_SubtractHint(aMinChange, nsChangeHint_UpdateOverflow);
+
   // It would be nice if we could make stronger assertions here; they
   // would let us simplify the ?: expressions below setting |content|
   // and |pseudoContent| in sensible ways as well as making what