Bug 501957 - Fix test_contextmenu_list.xul to deal with fractional positions. r=enndeakin

toolkit/content/tests/widgets/test_contextmenu_list.xul

@@ -156,8 +156,8 @@ function checkContextMenu(event)
   var frombase = (gTestId == -1 || gTestId == 1);
   if (!frombase)
     rect = event.originalTarget.getBoundingClientRect();
-  left = frombase ? rect.left + 7 : rect.left;
-  top = frombase ? rect.top + 4 : rect.bottom;
+  left = Math.round(frombase ? rect.left + 7 : rect.left);
+  top = Math.round(frombase ? rect.top + 4 : rect.bottom);
 
   is(event.clientX, left, gTestElement + " clientX " + gSelectionStep + " " + gTestId + "," + frombase);
   is(event.clientY, top, gTestElement + " clientY " + gSelectionStep + " " + gTestId);