track playing state: only dispatch playing on first start

Per review: playing event should only fire on first start, not
on every resume from pause. Add _playing field, reset on load().

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

@@ -76,9 +76,21 @@
     audio.pause();
     testing.expectEqual('play,playing,pause', events.join(','));
 
-    // Load: fires emptied
+    // Third play: resume from pause, fires play only (not playing)
+    audio.play();
+    testing.expectEqual('play,playing,pause,play', events.join(','));
+
+    // Pause again
+    audio.pause();
+    testing.expectEqual('play,playing,pause,play,pause', events.join(','));
+
+    // Load: resets state, fires emptied
     audio.load();
-    testing.expectEqual('play,playing,pause,emptied', events.join(','));
+    testing.expectEqual('play,playing,pause,play,pause,emptied', events.join(','));
+
+    // Play after load: fires play + playing again (fresh start)
+    audio.play();
+    testing.expectEqual('play,playing,pause,play,pause,emptied,play,playing', events.join(','));
   }
 </script>
 

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

@@ -61,6 +61,7 @@ _playback_rate: f64 = 1.0,
 _ready_state: ReadyState = .HAVE_NOTHING,
 _network_state: NetworkState = .NETWORK_EMPTY,
 _error: ?*MediaError = null,
+_playing: bool = false,
 
 pub fn asElement(self: *Media) *Element {
     return self._proto._proto;
@@ -144,7 +145,10 @@ pub fn play(self: *Media, page: *Page) !void {
     self._network_state = .NETWORK_IDLE;
     if (was_paused) {
         try self.dispatchEvent("play", page);
-        try self.dispatchEvent("playing", page);
+        if (!self._playing) {
+            self._playing = true;
+            try self.dispatchEvent("playing", page);
+        }
     }
 }
 
@@ -157,6 +161,7 @@ pub fn pause(self: *Media, page: *Page) !void {
 
 pub fn load(self: *Media, page: *Page) !void {
     self._paused = true;
+    self._playing = false;
     self._current_time = 0;
     self._ready_state = .HAVE_NOTHING;
     self._network_state = .NETWORK_LOADING;