Have to invalidate the mute button when changing the volume

LayoutTests/fast/repaint/video-unmute-repaint.html

Index: LayoutTests/fast/repaint/video-unmute-repaint.html
diff --git a/LayoutTests/fast/repaint/video-mute-repaint.html b/LayoutTests/fast/repaint/video-unmute-repaint.html
similarity index 85%
copy from LayoutTests/fast/repaint/video-mute-repaint.html
copy to LayoutTests/fast/repaint/video-unmute-repaint.html
index b009985d7737aaf00419897b6e15323094e9ef1a..528cbf599d398405bb56e5e538943ac645bd5373 100644
--- a/LayoutTests/fast/repaint/video-mute-repaint.html
+++ b/LayoutTests/fast/repaint/video-unmute-repaint.html
@@ -8,6 +8,8 @@
 <video id="v" controls autoload src="../../media/content/test.ogv">
 </video>
 
+<p>This tests that we repaint the mute button when we change the volume</p>
+
 <script>
     var video = document.getElementById("v");
     video.addEventListener("canplaythrough", runTest, true);
@@ -15,10 +17,11 @@
         window.testRunner.waitUntilDone();
 
     function repaintTest() {
-        video.volume = 0;
+        video.volume = 0.5;
     }
 
     function runTest() {
+        video.volume = 0;
         runRepaintTest();
 
         if (window.testRunner)