Fix HTMLMediaElement "direction of playback" behavior.

LayoutTests/media/media-ended.html

Index: LayoutTests/media/media-ended.html
diff --git a/LayoutTests/media/media-ended.html b/LayoutTests/media/media-ended.html
index 0a96fcceb76f7dacdec1c41c8bb222b3a26c6b11..4a9841c688c4b3fede090c5359735464bfeeeb3b 100644
--- a/LayoutTests/media/media-ended.html
+++ b/LayoutTests/media/media-ended.html
@@ -22,8 +22,19 @@
                 switch (++endedCount)
                 {
                     case 1:
+                        testExpected("audio.playbackRate", 0, ">");
                         testExpected("audio.ended", true);
 
+                        // Verify ended stays true even if playbackRate == 0
+                        // since that is technically still "forward".
+                        run("audio.playbackRate = 0");
+                        testExpected("audio.ended", true);
+
+                        // Verify "backward" playback causes ended to become false.
+                        run("audio.playbackRate = -0.1");
+                        testExpected("audio.ended", false);
+
+
                         // Change src but don't seek so that internal state isn't reset.
                         audio.src = findMediaFile("audio", "content/silence")
                         testExpected("audio.ended", false);