Remove more testRunner.display() calls from LayoutTests

LayoutTests/svg/custom/non-scaling-stroke-update.svg

 <svg xmlns="http://www.w3.org/2000/svg" xmlns:xlink="http://www.w3.org/1999/xlink">
   <!-- Test for crbug.com/250001 -->
   <g transform="scale(4)">
     <rect id="clear_rect" width="100%" height="100%"/>
     <rect id="rect" x="25" y="25" width="25" height="25" fill="green" stroke-width="1" stroke="black"/>
   </g>
 
   <script>
     if (window.testRunner) {
-        testRunner.display();
         testRunner.waitUntilDone();
+    }
+    window.requestAnimationFrame(function() {
         setTimeout(runTest, 0);
-    } else {
-        setTimeout(runTest, 200);
-    }
+    });
 
     function runTest() {
-        document.getElementById('clear_rect').setAttribute('fill', 'white');
-        document.getElementById('rect').setAttribute('vector-effect', 'non-scaling-stroke');
-        if (window.testRunner)
-            testRunner.notifyDone();
+        document.getElementById('clear_rect').setAttribute('fill', 'white');
+        document.getElementById('rect').setAttribute('vector-effect', 'non-scaling-stroke');
+        if (window.testRunner)
+            testRunner.notifyDone();
     }
   </script>
 </svg>