Convert to calls of GetOffsetTo from retained layers to GetOffsetToCrossDoc. r=roc on irc

layout/base/FrameLayerBuilder.cpp

@@ -909,7 +909,7 @@ ContainerState::ProcessDisplayItems(const nsDisplayList& aList,
       nsIFrame* activeScrolledRoot =
         nsLayoutUtils::GetActiveScrolledRootFor(f, mBuilder->ReferenceFrame(),
                                                 &offsetToActiveScrolledRoot);
-      NS_ASSERTION(offsetToActiveScrolledRoot == f->GetOffsetTo(activeScrolledRoot),
+      NS_ASSERTION(offsetToActiveScrolledRoot == f->GetOffsetToCrossDoc(activeScrolledRoot),
                    "Wrong offset");
       if (item->IsFixedAndCoveringViewport(mBuilder)) {
         // Make its active scrolled root be the active scrolled root of

layout/generic/nsGfxScrollFrame.cpp

@@ -1651,7 +1651,7 @@ void nsGfxScrollFrameInner::ScrollVisual(nsIntPoint aPixDelta)
   if (flags & nsIFrame::INVALIDATE_NO_THEBES_LAYERS) {
     // XXX fix this to transform rectangle properly
     InvalidateFixedBackgroundFrames(displayRoot, mScrolledFrame,
-      GetScrollPortRect() + mOuter->GetOffsetTo(displayRoot));
+      GetScrollPortRect() + mOuter->GetOffsetToCrossDoc(displayRoot));
   }
 }