Fix LayoutTests that assume canplay, playing, and canplaythrough will only fire once.

LayoutTests/media/video-frame-size-change.html

Index: LayoutTests/media/video-frame-size-change.html
diff --git a/LayoutTests/media/video-frame-size-change.html b/LayoutTests/media/video-frame-size-change.html
index 2048725e951f358cb0c426be6fecaa60c12ed917..653309e1e71a08147f68a34a0213724ad9cb8284 100644
--- a/LayoutTests/media/video-frame-size-change.html
+++ b/LayoutTests/media/video-frame-size-change.html
@@ -30,6 +30,8 @@
 
                     video.play();
                     video_fixed_size.play();
+                    video.removeEventListener('canplay', oncanplay);
+                    video_fixed_size.removeEventListener('canplay', oncanplay);
                 };
                 video.addEventListener('canplay', oncanplay);
                 video_fixed_size.addEventListener('canplay', oncanplay);
@@ -40,6 +42,9 @@
                         return;
                     }
 
+                    video.removeEventListener('playing', onplaying);
+                    video_fixed_size.removeEventListener('playing', onplaying);
+
                     // Make sure both videos play for a bit.
                     function ontimeupdate(e) {
                         if (e.target.currentTime > 1.0) {