diff --git a/mozilla/layout/generic/nsGfxScrollFrame.cpp b/mozilla/layout/generic/nsGfxScrollFrame.cpp
index b5cf3fcd0ac..77c958f29dc 100644
--- a/mozilla/layout/generic/nsGfxScrollFrame.cpp
+++ b/mozilla/layout/generic/nsGfxScrollFrame.cpp
@@ -691,13 +691,11 @@ nsHTMLScrollFrame::GetPadding(nsMargin& aMargin)
   return NS_OK;
 }
 
-NS_IMETHODIMP
-nsHTMLScrollFrame::IsCollapsed(nsBoxLayoutState& aBoxLayoutState,
-                                PRBool& aCollapsed)
+PRBool
+nsHTMLScrollFrame::IsCollapsed(nsBoxLayoutState& aBoxLayoutState)
 {
   // We're never collapsed in the box sense.
-  aCollapsed = PR_FALSE;
-  return NS_OK;
+  return PR_FALSE;
 }
 
 NS_IMETHODIMP
diff --git a/mozilla/layout/generic/nsGfxScrollFrame.h b/mozilla/layout/generic/nsGfxScrollFrame.h
index 565e5a6e34d..5181a329a1a 100644
--- a/mozilla/layout/generic/nsGfxScrollFrame.h
+++ b/mozilla/layout/generic/nsGfxScrollFrame.h
@@ -260,8 +260,7 @@ public:
   virtual nscoord GetMinWidth(nsIRenderingContext *aRenderingContext);
   virtual nscoord GetPrefWidth(nsIRenderingContext *aRenderingContext);
   NS_IMETHOD GetPadding(nsMargin& aPadding);
-  NS_IMETHOD IsCollapsed(nsBoxLayoutState& aBoxLayoutState,
-                         PRBool& aCollapsed);
+  virtual PRBool IsCollapsed(nsBoxLayoutState& aBoxLayoutState);
   
   NS_IMETHOD Reflow(nsPresContext*          aPresContext,
                     nsHTMLReflowMetrics&     aDesiredSize,