Bug 558705 - [Debug] mochitests-4: intermittent "test_value_cloning.html | Test timed out."; (Av1) Increase timeout factor to 4 from 3.

r=dbaron a=(test only).

layout/style/test/test_value_cloning.html

@@ -22,7 +22,7 @@ var iframe = document.getElementById("iframe");
 var current_item;
 
 SimpleTest.waitForExplicitFinish();
-SimpleTest.requestLongerTimeout(3);
+SimpleTest.requestLongerTimeout(4);
 
 for (var prop in gCSSProperties) {
   var info = gCSSProperties[prop];