Backed out changeset 91898a35b414 (bug 1224251)

layout/style/nsStyleStruct.cpp

@@ -2950,9 +2950,6 @@ nsChangeHint nsStyleDisplay::CalcDifference(const nsStyleDisplay& aOther) const
       NS_UpdateHint(hint, nsChangeHint_RepaintFrame);
     } else {
       NS_UpdateHint(hint, nsChangeHint_UpdateOpacityLayer);
-      if ((mOpacity == 1.0f) != (aOther.mOpacity == 1.0f)) {
-        NS_UpdateHint(hint, nsChangeHint_UpdateUsesOpacity);
-      }
     }
   }
 

layout/style/nsStyleStruct.h

@@ -2201,7 +2201,6 @@ struct nsStyleDisplay {
     // All the parts of FRAMECHANGE are present in CalcDifference.
     return nsChangeHint(NS_STYLE_HINT_FRAMECHANGE |
                         nsChangeHint_UpdateOpacityLayer |
-                        nsChangeHint_UpdateUsesOpacity |
                         nsChangeHint_UpdateTransformLayer |
                         nsChangeHint_UpdateOverflow |
                         nsChangeHint_UpdatePostTransformOverflow |