Use nsIFrame::GetBorderRadii so that we pick up when it is overridden. (Bug 459144, patch 7) r=roc a2.0=blocking:beta6+

layout/forms/nsFieldSetFrame.cpp

@@ -279,6 +279,8 @@ nsFieldSetFrame::PaintBorderBackground(nsIRenderingContext& aRenderingContext,
      
   // if the border is smaller than the legend. Move the border down
   // to be centered on the legend. 
+  // FIXME: This means border-radius clamping is incorrect; we should
+  // override nsIFrame::GetBorderRadii.
   if (topBorder < mLegendRect.height)
     yoff = (mLegendRect.height - topBorder)/2;