Fix some async repaint tests

LayoutTests/svg/custom/mask-invalidation.svg

 <?xml version="1.0" encoding="utf-8"?>
 <svg xmlns="http://www.w3.org/2000/svg" xmlns:xlink="http://www.w3.org/1999/xlink" onload="runRepaintAndPixelTest()">
 <script xlink:href="../../fast/repaint/resources/text-based-repaint.js"/>
 <script>
+window.testIsAsync = true;
 function draw(x, y) {
     var maskrect = document.getElementById("maskRect");
     maskrect.setAttribute("transform", "translate(" + x + "," + y + ")");
 
     var rect = document.createElementNS('http://www.w3.org/2000/svg', 'rect');
     rect.setAttribute("x", x);
     rect.setAttribute("y", y);
     rect.setAttribute("width", 453);
     rect.setAttribute("height", 299);
     rect.setAttribute("fill", "green");
     rect.setAttribute("mask", "url(#mask)");
 
     var root = document.getElementById("root");
     while (root.firstChild) {
         root.removeChild(root.firstChild);
     }
     root.appendChild(rect);
 }
 
 function repaintTest() {
-    if (window.testRunner)
-        testRunner.waitUntilDone();
-
     draw(150, 50);
     requestAnimationFrame(function() {
         draw(50, 50);
-        if (window.testRunner)
-            testRunner.notifyDone();
+        finishRepaintTest();
     });
 }
 
 </script>
 <defs>
 <mask id="mask" maskUnits="userSpaceOnUse" maskContentUnits="userSpaceOnUse">
     <rect id="maskRect" x="50" y="50" width="460" height="316" fill="white" />
 </mask>
 </defs>
 <g id="root">
     <rect x="50" y="50" width="453" height="299" fill="green" mask="url(#mask)"/>
 </g>
 </svg>