dispatch play, playing, pause, and emptied events from HTMLMediaElement

play(), pause(), and load() now fire the corresponding DOM events,
matching the HTMLMediaElement spec behavior.

src/browser/tests/element/html/media.html

@@ -50,6 +50,27 @@
   }
 </script>
 
+<script id="play_pause_events">
+  {
+    const audio = document.createElement('audio');
+    const events = [];
+
+    audio.addEventListener('play', () => events.push('play'));
+    audio.addEventListener('playing', () => events.push('playing'));
+    audio.addEventListener('pause', () => events.push('pause'));
+    audio.addEventListener('emptied', () => events.push('emptied'));
+
+    audio.play();
+    testing.expectEqual('play,playing', events.join(','));
+
+    audio.pause();
+    testing.expectEqual('play,playing,pause', events.join(','));
+
+    audio.load();
+    testing.expectEqual('play,playing,pause,emptied', events.join(','));
+  }
+</script>
+
 <script id="volume_muted">
   {
     const audio = document.getElementById('audio1');

src/browser/webapi/element/html/Media.zig

@@ -23,6 +23,7 @@ const Page = @import("../../../Page.zig");
 const Node = @import("../../Node.zig");
 const Element = @import("../../Element.zig");
 const HtmlElement = @import("../Html.zig");
+const Event = @import("../../Event.zig");
 pub const Audio = @import("Audio.zig");
 pub const Video = @import("Video.zig");
 const MediaError = @import("../../media/MediaError.zig");
@@ -136,25 +137,32 @@ fn isMaybeSupported(mime_type: []const u8) bool {
     return false;
 }
 
-pub fn play(self: *Media) void {
+pub fn play(self: *Media, page: *Page) !void {
     self._paused = false;
     self._ready_state = .HAVE_ENOUGH_DATA;
     self._network_state = .NETWORK_IDLE;
-    // TODO: Could dispatch 'play' and 'playing' events
+    try self.dispatchEvent("play", page);
+    try self.dispatchEvent("playing", page);
 }
 
-pub fn pause(self: *Media) void {
+pub fn pause(self: *Media, page: *Page) !void {
     self._paused = true;
-    // TODO: Could dispatch 'pause' event
+    try self.dispatchEvent("pause", page);
 }
 
-pub fn load(self: *Media) void {
+pub fn load(self: *Media, page: *Page) !void {
     self._paused = true;
     self._current_time = 0;
     self._ready_state = .HAVE_NOTHING;
     self._network_state = .NETWORK_LOADING;
     self._error = null;
-    // TODO: Could dispatch events
+    try self.dispatchEvent("emptied", page);
+}
+
+fn dispatchEvent(self: *Media, name: []const u8, page: *Page) !void {
+    const event = try Event.init(name, null, page);
+    defer if (!event._v8_handoff) event.deinit(false);
+    try page._event_manager.dispatch(self.asElement().asEventTarget(), event);
 }
 
 pub fn getPaused(self: *const Media) bool {