Bug 1360568 - Update wheel event coordinates to account for different styling on Ubuntu 16.04. r=jmaher

MozReview-Commit-ID: 5t2vTbsdzg4

--HG--
extra : rebase_source : 86965bb9617b0c218d3ac32ad8b6c9070312e0db

dom/events/test/test_bug946632.html

@@ -144,7 +144,7 @@ function nextTest()
   window.waitForAllPaintsFlushed(function() {
     prepare(test.check);
 
-    sendWheelAndPaint(input, 5, 5, test.event, function() {
+    sendWheelAndPaint(input, 8, 6, test.event, function() {
       // Do nothing - we wait for the scroll event.
     });
   });