Bug 1042772. Set the dirty rect relative to the current frame, not the reference frame. r=roc

The offsetToReferenceFrame is to the reference frame for this, since we are transformed we are the reference frame, so the offset was 0,0. So the computation still produced correct results.

layout/generic/nsFrame.cpp

@@ -2105,7 +2105,7 @@ nsIFrame::BuildDisplayListForStackingContext(nsDisplayListBuilder* aBuilder,
     clipState.Restore();
     // Revert to the dirtyrect coming in from the parent, without our transform
     // taken into account.
-    buildingDisplayList.SetDirtyRect(aDirtyRect + offsetToReferenceFrame);
+    buildingDisplayList.SetDirtyRect(aDirtyRect);
 
     if (Preserves3DChildren()) {
       WrapPreserve3DList(this, aBuilder, &resultList);