dont paint border collapse borders if the damage area is not covered by the borders, bug 225266 r/sr=dbaron

layout/html/table/src/nsTableFrame.cpp

@@ -6655,6 +6655,8 @@ nsTableFrame::PaintBCBorders(nsIPresContext*      aPresContext,
     x += size.width;
   }
 
+  if (!haveIntersect)
+    return;
   // iterate the cell map and build up border segments
   nsRect damageArea(startColIndex, startRowIndex, 1 + endColIndex - startColIndex, 
                     1 + endRowIndex - startRowIndex);

layout/tables/nsTableFrame.cpp

@@ -6655,6 +6655,8 @@ nsTableFrame::PaintBCBorders(nsIPresContext*      aPresContext,
     x += size.width;
   }
 
+  if (!haveIntersect)
+    return;
   // iterate the cell map and build up border segments
   nsRect damageArea(startColIndex, startRowIndex, 1 + endColIndex - startColIndex, 
                     1 + endRowIndex - startRowIndex);