HTML5VideoView: Disable seek operation while start to play live streaming

Summary:
- Live streaming doesn't support seek operation
- Disable seekTo(0) while start to play the streaming source

Change-Id: I4153fc583c189d28937829c79a79c7035240d115

Test Plan: verified

Reviewers: randall.rushing, synergy

Reviewed By: synergy

Differential Revision: http://review.codefirex.com/D449