hopefully fix addChunk

server/djrandom/frontend/static/player.js

@@ -114,12 +114,13 @@ djr.Playlist.prototype.addChunk = function(playlist_chunk) {
   djr.debug('adding chunk to playlist ' + this.uuid);
   chunk_id = this.next_chunk_id++;
   var songs = [];
+  var playlist = this;
   $.each(playlist_chunk.songs, function(idx, song) {
-    if (this.song_map[song]) {
+    if (playlist.song_map[song]) {
       return;
     }
     songs.push(song);
-    this.song_map[song] = chunk_id;
+    playlist.song_map[song] = chunk_id;
   });
   this.chunk_map[chunk_id] = new djr.PlaylistChunk(songs);
   this.chunks.push(chunk_id);