[Multi period] Seek towards the end of first period duration stalls playback

Created by: KarishmaBagga

This is after taking in fix for #285 (closed) . I observe that for the mpd http://dash.edgesuite.net/dash264/TestCases/5a/1/manifest.mpd, if we seek to around 2:40 (near the end of period duration of 3:08), the playback stalls after a few secs with audio buffer length around 1.9 and errors on console

Waiting for more audio buffer before starting playback. Debug.js:48 Stalling audio Buffer: audio

I think this is because we are assuming the total duration is 6:08?