Bug 604885 commit backout merge. a=backout

toolkit/content/widgets/videocontrols.xml

@@ -718,15 +718,13 @@
                     else
                         element.removeAttribute("immediate");
 
-                    // We must force style resolution (by accessing element.clientTop)
-                    // in order to ensure our size changes correctly when the status
-                    // overlay hides and shows.
                     if (fadeIn) {
                         element.setAttribute("hidden", false);
-                        element.clientTop;
+                        // force style resolution, so that transition begins
+                        // when we remove the attribute.
+                        getComputedStyle(element, "").display;
                         element.removeAttribute("fadeout");
                     } else {
-                        element.clientTop;
                         element.setAttribute("fadeout", true);
                     }
                 },