Validate finiteness of HTMLMediaElement properties.

LayoutTests/media/media-controller-playback.html

Index: LayoutTests/media/media-controller-playback.html
diff --git a/LayoutTests/media/media-controller-playback.html b/LayoutTests/media/media-controller-playback.html
index 10db0a71e5799c68f539cba9aea2ddc82f1a8198..cc765d6c0b2ff98a2cbd361daa9771facd79e91b 100644
--- a/LayoutTests/media/media-controller-playback.html
+++ b/LayoutTests/media/media-controller-playback.html
@@ -22,6 +22,11 @@
         function canplaythrough() {
             consoleWrite("EVENT(canplaythrough)");
             controller.removeEventListener('canplaythrough', canplaythrough, true);
+
+            testException("controller.currentTime = -Infinity", "TypeError: Failed to set the 'currentTime' property on 'MediaController': The value provided is infinite.");
+            testException("controller.currentTime = Infinity", "TypeError: Failed to set the 'currentTime' property on 'MediaController': The value provided is infinite.");
+            testException("controller.currentTime = NaN", "TypeError: Failed to set the 'currentTime' property on 'MediaController': The value provided is not a number.");
+
             controller.addEventListener('playing', playing, true);
             run('controller.play()');
         }