Convert some repaint tests to not call display()

LayoutTests/media/media-document-audio-repaint.html

+<style>
+    body {
+        overflow: hidden
+    }
+    pre {
+        position: absolute;
+        top: 10000px;
+    }
+</style>
+<script src="../resources/run-after-display.js"></script>
 <script>
     if (window.testRunner)
         testRunner.waitUntilDone();
 
     function onPause()
     {
         var videoElement = document.getElementById("fr").contentDocument.querySelector("video");
-        if (window.testRunner)
-            testRunner.display();
-        videoElement.currentTime = videoElement.duration * 0.50;
+        window.internals.startTrackingRepaints(document);
+        runAfterDisplay(function() {
+            videoElement.currentTime = videoElement.duration * 0.50;
+        });
     }
 
     function onSeeked()
     {
+        var repaintRects = window.internals.repaintRectsAsText(document);
+        var pre = document.createElement('pre');
+        document.body.appendChild(pre);
+        pre.textContent += repaintRects;
+        window.internals.stopTrackingRepaints(document);
+
         if (window.testRunner)
             testRunner.notifyDone();
     }
 
     function frameLoaded()
     {
         var videoElement = document.getElementById("fr").contentDocument.querySelector("video");
         videoElement.addEventListener("pause", onPause, false);
         videoElement.addEventListener("seeked", onSeeked, false);
         // The MediaDocument has AUTOPLAY set, make sure we're paused.
         videoElement.pause();
     }
 </script>
 <p>
     This tests that in a standalone media document with audio content, the media element repaints correctly
     while playing.
 </p>
 <iframe src="content/silence.wav" id="fr" width=380 height=330 onload="frameLoaded()"></iframe>
 <script>// To produce the same layout as before iframe was moved down to avoid rebaselines of different platforms.
 // https://bugs.webkit.org/show_bug.cgi?id=54942
 </script>