Bug 992077 patch 2 - Use nsChangeHint_UpdateParentOverflow for changes to the top, right, bottom, and left properties. r=mats

These are the properties currently using UpdateOverflow where dynamic
changes of the properties do not affect the element's own overflow
areas, but instead affect the element's influence on its parent's
overflow areas.

layout/style/nsStyleStruct.cpp

@@ -1618,7 +1618,7 @@ nsChangeHint nsStylePosition::CalcDifference(const nsStylePosition& aOther) cons
   if (mOffset != aOther.mOffset) {
     if (IsAutonessEqual(mOffset, aOther.mOffset)) {
       NS_UpdateHint(hint, nsChangeHint(nsChangeHint_RecomputePosition |
-                                       nsChangeHint_UpdateOverflow));
+                                       nsChangeHint_UpdateParentOverflow));
     } else {
       return NS_CombineHint(hint, nsChangeHint_AllReflowHints);
     }

layout/style/nsStyleStruct.h

@@ -1331,7 +1331,7 @@ struct nsStylePosition {
   static nsChangeHint MaxDifference() {
     return NS_CombineHint(NS_STYLE_HINT_REFLOW,
                           nsChangeHint(nsChangeHint_RecomputePosition |
-                                       nsChangeHint_UpdateOverflow));
+                                       nsChangeHint_UpdateParentOverflow));
   }
   static nsChangeHint MaxDifferenceNeverInherited() {
     // CalcDifference can return both nsChangeHint_ClearAncestorIntrinsics and