Fix some async repaint tests

LayoutTests/fast/repaint/repaint-during-scroll-with-zoom.html

Index: LayoutTests/fast/repaint/repaint-during-scroll-with-zoom.html
diff --git a/LayoutTests/fast/repaint/repaint-during-scroll-with-zoom.html b/LayoutTests/fast/repaint/repaint-during-scroll-with-zoom.html
index 17e5cd340d16561951d247fc233de7618b2ea815..8b4bc4e60ee898b194373de1627478f483bac46a 100644
--- a/LayoutTests/fast/repaint/repaint-during-scroll-with-zoom.html
+++ b/LayoutTests/fast/repaint/repaint-during-scroll-with-zoom.html
@@ -29,15 +29,12 @@
         frame.scrollBy(100, 100);
     </script>
     <script>
+        window.testIsAsync = true;
         function repaintTest()
         {
-            if (window.testRunner) {
-                testRunner.waitUntilDone();
-                frame.onscroll = function() {
-                    if (window.testRunner)
-                        testRunner.notifyDone();
-                };
-            }
+            frame.onscroll = function() {
+                finishRepaintTest();
+            };
             frame.scrollBy(-90, -90);
         }
     </script>