Bug 316500. Fix merge regression so that fixed-background tables display correctly. r+sr=mats,a=damon

layout/tables/nsTableFrame.cpp

@@ -1262,8 +1262,7 @@ nsDisplayTableItem::GetBounds(nsDisplayListBuilder* aBuilder) {
 }
 
 PRBool
-nsDisplayTableItem::IsVaryingRelativeToFrame(nsDisplayListBuilder* aBuilder,
-                                             nsIFrame* aAncestorFrame)
+nsDisplayTableItem::IsVaryingRelativeToMovingFrame(nsDisplayListBuilder* aBuilder)
 {
   if (!mPartHasFixedBackground)
     return PR_FALSE;
@@ -1274,8 +1273,9 @@ nsDisplayTableItem::IsVaryingRelativeToFrame(nsDisplayListBuilder* aBuilder,
   // will move relative to its viewport, which means this display item will
   // change when it is moved.  If they are in different documents, we do not
   // want to return true because mFrame won't move relative to its viewport.
-  return mFrame == aAncestorFrame ||
-    nsLayoutUtils::IsProperAncestorFrame(aAncestorFrame, mFrame);
+  nsIFrame* rootMover = aBuilder->GetRootMovingFrame();
+  return mFrame == rootMover ||
+    nsLayoutUtils::IsProperAncestorFrame(rootMover, mFrame);
 }
 
 /* static */ void

layout/tables/nsTableFrame.h

@@ -79,8 +79,7 @@ public:
   nsDisplayTableItem(nsIFrame* aFrame) : nsDisplayItem(aFrame),
       mPartHasFixedBackground(PR_FALSE) {}
 
-  virtual PRBool IsVaryingRelativeToFrame(nsDisplayListBuilder* aBuilder,
-                                          nsIFrame* aAncestorFrame);
+  virtual PRBool IsVaryingRelativeToMovingFrame(nsDisplayListBuilder* aBuilder);
   // With collapsed borders, parts of the collapsed border can extend outside
   // the table part frames, so allow this display element to blow out to our
   // overflow rect. This is also useful for row frames that have spanning