Set the used padding on the scrolled frame, since we're munging its padding.

Bug 370794, r+sr=dbaron

layout/generic/nsGfxScrollFrame.cpp

@@ -440,6 +440,13 @@ nsHTMLScrollFrame::ReflowScrolledFrame(const ScrollReflowState& aState,
   if (!aFirstPass)
     mInner.mScrolledFrame->AddStateBits(NS_FRAME_IS_DIRTY);
 
+  // We're forcing the padding on our scrolled frame, so let it know what that
+  // padding is.
+  mInner.mScrolledFrame->
+    SetProperty(nsGkAtoms::usedPaddingProperty,
+                new nsMargin(aState.mReflowState.mComputedPadding),
+                nsCSSOffsetState::DestroyMarginFunc);  
+  
   // Pass PR_FALSE for aInit so we can pass in the correct padding
   nsHTMLReflowState kidReflowState(presContext, aState.mReflowState,
                                    mInner.mScrolledFrame,

layout/generic/nsHTMLReflowState.cpp

@@ -1923,11 +1923,12 @@ nsHTMLReflowState::CalcLineHeight(nsPresContext* aPresContext,
   return lineHeight;
 }
 
-static void
-DestroyMarginFunc(void*    aFrame,
-                  nsIAtom* aPropertyName,
-                  void*    aPropertyValue,
-                  void*    aDtorData)
+/* static */
+void
+nsCSSOffsetState::DestroyMarginFunc(void*    aFrame,
+                                    nsIAtom* aPropertyName,
+                                    void*    aPropertyValue,
+                                    void*    aDtorData)
 {
   delete NS_STATIC_CAST(nsMargin*, aPropertyValue);
 }

layout/generic/nsHTMLReflowState.h

@@ -172,6 +172,12 @@ public:
                    const nsMargin *aBorder = nsnull,
                    const nsMargin *aPadding = nsnull);
 
+  // Destructor for usedPaddingProperty
+  static void DestroyMarginFunc(void*    aFrame,
+                                nsIAtom* aPropertyName,
+                                void*    aPropertyValue,
+                                void*    aDtorData);
+
 private:
   // Computes margin values from the specified margin style information, and
   // fills in the mComputedMargin member