Fix offsetWidth,clientWidth and scrollWidth for empty block elements. Bug

186516, r+sr=roc

content/html/content/src/nsGenericHTMLElement.cpp

@@ -621,6 +621,11 @@ nsGenericHTMLElement::GetOffsetRect(nsRect& aRect, nsIContent** aOffsetParent)
     next->GetNextInFlow(&next);
   } while (next);
 
+  if (rcFrame.IsEmpty()) {
+    // It could happen that all the rects are empty (eg zero-width or
+    // zero-height).  In that case, use the first rect for the frame.
+    rcFrame = frame->GetRect();
+  }
 
   nsIContent *docElement = mDocument->GetRootContent();