Don't register fillBuffer checks until after a media playlist has downloaded

Fixes #110. Fixes #116. If timeupdates were being firing without a media playlist available yet, fillBuffer would dereference a property on undefined and blow up. Timeupdates occur manually on a fixed interval when using the Flash tech so this was guaranteed to happen whenever the media playlist was unretrievable. To avoid this, wait to register buffer checks until a media playlist has been successfully downloaded. As it turns out, this is the same moment we normally trigger loadedmetadata so it was possible to transform a loadedmetadata handler into a direct call to fillBuffer.

@@ -394,8 +394,13 @@ var
             } else {
               player.duration(totalDuration(parser.manifest));
             }
+
+            // periodicaly check if the buffer needs to be refilled
+            player.on('timeupdate', fillBuffer);
+
             player.trigger('loadedmanifest');
             player.trigger('loadedmetadata');
+            fillBuffer();
             return;
           }
 
@@ -536,9 +541,6 @@ var
       player.hls.sourceBuffer = sourceBuffer;
       sourceBuffer.appendBuffer(segmentParser.getFlvHeader());
 
-      player.on('loadedmetadata', fillBuffer);
-      player.on('timeupdate', fillBuffer);
-
       player.hls.mediaIndex = 0;
       downloadPlaylist(srcUrl);
     });

@@ -239,6 +239,24 @@ test('downloads media playlists after loading the master', function() {
               'first segment requested');
 });
 
+test('timeupdates do not check to fill the buffer until a media playlist is ready', function() {
+  var urls = [];
+  window.XMLHttpRequest = function() {
+    this.open = function(method, url) {
+      urls.push(url);
+    };
+    this.send = function() {};
+  };
+  player.hls('manifest/media.m3u8');
+  videojs.mediaSources[player.currentSrc()].trigger({
+    type: 'sourceopen'
+  });
+  player.trigger('timeupdate');
+
+  strictEqual(1, urls.length, 'one request was made');
+  strictEqual('manifest/media.m3u8', urls[0], 'media playlist requested');
+});
+
 test('calculates the bandwidth after downloading a segment', function() {
   player.hls('manifest/media.m3u8');
   videojs.mediaSources[player.currentSrc()].trigger({