Don't try to include the selection area in our text-decoration overflow if

we're not selected.  Bug 429595, r+sr=roc, a=beltzner

layout/generic/nsTextFrameThebes.cpp

@@ -3689,7 +3689,8 @@ nsTextFrame::UnionTextDecorationOverflow(nsPresContext* aPresContext,
   // When this frame is not selected, the text-decoration area must be in
   // frame bounds.
   float ratio;
-  if (!HasSelectionOverflowingDecorations(aPresContext, &ratio))
+  if (!(GetStateBits() & NS_FRAME_SELECTED_CONTENT) ||
+      !HasSelectionOverflowingDecorations(aPresContext, &ratio))
     return;
 
   nsLineLayout::CombineTextDecorations(aPresContext,