Fix seek issue when first playing live streams

When you first called play() on a live stream, the seek wouldn't complete because of a condition in fillBuffer() that prevented buffering until the player had started. Allow fillBuffer() to begin buffering in a live stream at a specified position, which ensures drainBuffer() will clean up the seek correctly.

@@ -317,7 +317,6 @@ videojs.Hls.prototype.setupMetadataCueTranslation_ = function() {
  * ended.
  */
 videojs.Hls.prototype.play = function() {
-  var media;
   if (this.ended()) {
     this.mediaIndex = 0;
   }
@@ -327,9 +326,7 @@ videojs.Hls.prototype.play = function() {
   if (this.duration() === Infinity &&
       this.playlists.media() &&
       !this.player().hasClass('vjs-has-started')) {
-    media = this.playlists.media();
-    this.mediaIndex = videojs.Hls.getMediaIndexForLive_(media);
-    this.setCurrentTime(videojs.Hls.Playlist.seekable(media).end(0));
+    this.setCurrentTime(this.seekable().end(0));
   }
 
   // delegate back to the Flash implementation
@@ -645,7 +642,8 @@ videojs.Hls.prototype.fillBuffer = function(offset) {
   // being buffering so we don't preload data that will never be
   // played
   if (!this.playlists.media().endList &&
-      !this.player().hasClass('vjs-has-started')) {
+      !this.player().hasClass('vjs-has-started') &&
+      offset === undefined) {
     return;
   }
 

@@ -1663,19 +1663,33 @@ test('updates the media index when a playlist reloads', function() {
 test('live playlist starts three target durations before live', function() {
   var mediaPlaylist;
   player.src({
-    src: 'http://example.com/manifest/liveStart30sBefore.m3u8',
+    src: 'live.m3u8',
     type: 'application/vnd.apple.mpegurl'
   });
   openMediaSource(player);
-  standardXHRResponse(requests.shift());
+  requests.shift().respond(200, null,
+                           '#EXTM3U\n' +
+                           '#EXT-X-MEDIA-SEQUENCE:101\n' +
+                           '#EXTINF:10,\n' +
+                           '0.ts\n' +
+                           '#EXTINF:10,\n' +
+                           '1.ts\n' +
+                           '#EXTINF:10,\n' +
+                           '2.ts\n' +
+                           '#EXTINF:10,\n' +
+                           '3.ts\n' +
+                           '#EXTINF:10,\n' +
+                           '4.ts\n');
 
   equal(player.hls.mediaIndex, 0, 'waits for the first play to start buffering');
   equal(requests.length, 0, 'no outstanding segment request');
 
   player.play();
   mediaPlaylist = player.hls.playlists.media();
-  equal(player.hls.mediaIndex, 6, 'mediaIndex is updated at play');
-  equal(player.currentTime(), videojs.Hls.Playlist.seekable(mediaPlaylist).end(0));
+  equal(player.hls.mediaIndex, 1, 'mediaIndex is updated at play');
+  equal(player.currentTime(), player.seekable().end(0));
+
+  equal(requests.length, 1, 'begins buffering');
 });
 
 test('does not reset live currentTime if mediaIndex is one beyond the last available segment', function() {