extend AudioContext webidl for output sink

* added unstable AudioContext partial with audio sink types
* unrelated to sink, but I also added latencyHint to AudioContextOptions as it's stable

crates/web-sys/webidls/enabled/AudioContext.webidl

@@ -10,8 +10,15 @@
  * liability, trademark and document use rules apply.
  */
 
+enum AudioContextLatencyCategory {
+    "balanced",
+    "interactive",
+    "playback"
+};
+
 dictionary AudioContextOptions {
-             float        sampleRate = 0;
+    (AudioContextLatencyCategory or double) latencyHint = "interactive";
+    float        sampleRate = 0;
 };
 
 [Pref="dom.webaudio.enabled",

crates/web-sys/webidls/unstable/AudioContext.webidl

@@ -0,0 +1,18 @@
+enum AudioSinkType {
+    "none"
+};
+
+dictionary AudioSinkOptions {
+    required AudioSinkType type;
+};
+
+partial dictionary AudioContextOptions {
+    (DOMString or AudioSinkOptions) sinkId;
+};
+
+partial interface AudioContext {
+  [SecureContext] readonly attribute (DOMString or AudioSinkInfo) sinkId;
+
+  [SecureContext] Promise<undefined> setSinkId ((DOMString or AudioSinkOptions) sinkId);
+  attribute EventHandler onsinkchange;
+};

crates/web-sys/webidls/unstable/AudioSinkInfo.webidl

@@ -0,0 +1,4 @@
+[Exposed=Window]
+interface AudioSinkInfo {
+    readonly attribute AudioSinkType type;
+};