Bug 539356 - Fix selectAtPoint.html test. r=mattwoodrow

dom/tests/mochitest/chrome/selectAtPoint.html

@@ -197,13 +197,23 @@
   }
 
   function onFrameLoad() {
-    frameLoad = true;
-    testReady();
+    // Exit the onload handler before trying the test, because we need
+    // to ensure that paint unsupression has happened.
+    setTimeout(function() {
+      frameLoad = true;
+      testReady();
+    }, 0);
   }
 
   function onPageLoad() {
-    pageLoad = true;
-    testReady();
+    // Exit the onload handler before trying the test, because we need
+    // to ensure that paint unsupression has happened
+    // XXXroc why do we need to separately test for the loading of the frame
+    // and a paint? That should not be necessary for this test.
+    setTimeout(function() {
+      pageLoad = true;
+      testReady();
+    }, 0);
   }
 
   function onPaint() {