Enable MediaSession WPT

tests/wpt/include.ini

@@ -119,6 +119,8 @@ skip: true
           skip: true
 [js]
   skip: false
+[mediasession]
+  skip: false
 [navigation-timing]
   skip: false
 [offscreen-canvas]

tests/wpt/metadata/mediasession/idlharness.window.js.ini

@@ -0,0 +1,16 @@
+[idlharness.window.html]
+  [MediaSession interface: calling setPositionState(MediaPositionState) on navigator.mediaSession with too few arguments must throw TypeError]
+    expected: FAIL
+
+  [MediaSession interface: navigator.mediaSession must inherit property "setPositionState(MediaPositionState)" with the proper type]
+    expected: FAIL
+
+  [MediaSession interface: operation setPositionState(MediaPositionState)]
+    expected: FAIL
+
+  [MediaMetadata interface: attribute artwork]
+    expected: FAIL
+
+  [MediaMetadata interface: new MediaMetadata() must inherit property "artwork" with the proper type]
+    expected: FAIL
+

tests/wpt/metadata/mediasession/mediametadata.html.ini

@@ -0,0 +1,43 @@
+[mediametadata.html]
+  [Test that MediaMetadata.artwork is Frozen]
+    expected: FAIL
+
+  [Test that MediaMetadat.artwork can't be modified]
+    expected: FAIL
+
+  [Test that resetting metadata to null is reflected]
+    expected: FAIL
+
+  [Test the default values for MediaMetadata with empty init dictionary]
+    expected: FAIL
+
+  [Test MediaImage default values]
+    expected: FAIL
+
+  [Test that mediaSession.metadata is properly set]
+    expected: FAIL
+
+  [Test that changes to metadata propagate properly]
+    expected: FAIL
+
+  [Test that MediaMetadata.artwork returns parsed urls]
+    expected: FAIL
+
+  [Test the different values allowed in MediaMetadata init dictionary]
+    expected: FAIL
+
+  [Test the default values for MediaMetadata with no init dictionary]
+    expected: FAIL
+
+  [Test that MediaImage.src is required]
+    expected: FAIL
+
+  [Test that MediaMetadata throws when setting an invalid url]
+    expected: FAIL
+
+  [Test that MediaMetadata.artwork will not expose unknown properties]
+    expected: FAIL
+
+  [Test that the base URL of MediaImage is the base URL of entry setting object]
+    expected: FAIL
+

tests/wpt/metadata/mediasession/positionstate.html.ini

@@ -0,0 +1,19 @@
+[positionstate.html]
+  [Test setPositionState with a null value]
+    expected: FAIL
+
+  [Test setPositionState with zero duration]
+    expected: FAIL
+
+  [Test setPositionState with a valid value for forward playback]
+    expected: FAIL
+
+  [Test setPositionState with optional position]
+    expected: FAIL
+
+  [Test setPositionState with only duration]
+    expected: FAIL
+
+  [Test setPositionState with optional playback rate]
+    expected: FAIL
+

tests/wpt/mozilla/tests/mozilla/interfaces.html

@@ -166,8 +166,10 @@ test_interfaces([
   "MediaElementAudioSourceNode",
   "MediaError",
   "MediaList",
+  "MediaMetadata",
   "MediaQueryList",
   "MediaQueryListEvent",
+  "MediaSession",
   "MessageChannel",
   "MessageEvent",
   "MessagePort",