added an assertion that will catch regressions associated with bug 25510

r=troy
a=jar


git-svn-id: svn://10.0.0.236/trunk@61439 18797224-902f-48f8-a5cc-f745e15eee43

mozilla/layout/generic/nsLineBox.cpp

@@ -388,6 +388,8 @@ nsLineBox::RemoveFloater(nsIFrame* aFrame)
 void
 nsLineBox::SetCombinedArea(const nsRect& aCombinedArea)
 {
+  NS_ASSERTION(aCombinedArea.width >= 0, "illegal width for combined area");
+  NS_ASSERTION(aCombinedArea.height >= 0, "illegal height for combined area");
   if (aCombinedArea != mBounds) {
     if (mData) {
       mData->mCombinedArea = aCombinedArea;