shaka-player: Shaka Player's seek bug with Firefox browser

Have you read the FAQ and checked for duplicate open issues? Yes

What version of Shaka Player are you using? 3.0.4

Can you reproduce the issue with our latest release version? yes

Can you reproduce the issue with the latest code from master? yes

Are you using the demo app or your own custom app? custom

If custom app, can you reproduce the issue using our demo app? yes

What browser and OS are you using? Firefox

For embedded devices (smart TVs, etc.), what model and firmware version are you using? None

What are the manifest and license server URIs? https://raw.githubusercontent.com/interlark/shaka-player-bug_fragmented-mp4-with-scenecut/master/demo/videos/BBB/master-no-scenecut.m3u8 https://raw.githubusercontent.com/interlark/shaka-player-bug_fragmented-mp4-with-scenecut/master/demo/videos/BBB/master.m3u8

https://raw.githubusercontent.com/interlark/shaka-player-bug_fragmented-mp4-with-scenecut/master/demo/videos/ElephantsDream/master-no-scenecut.m3u8 https://raw.githubusercontent.com/interlark/shaka-player-bug_fragmented-mp4-with-scenecut/master/demo/videos/ElephantsDream/master.m3u8

https://raw.githubusercontent.com/interlark/shaka-player-bug_fragmented-mp4-with-scenecut/master/demo/videos/Sintel/master-no-scenecut.m3u8 https://raw.githubusercontent.com/interlark/shaka-player-bug_fragmented-mp4-with-scenecut/master/demo/videos/Sintel/master.m3u8

What did you do? Please, see special repo for this info.

What did you expect to happen? Navigate through timecodes (like youtube’s 3:20, 1:21, you know) without gitches and freezes.

What actually happened? Video freezes and glitches on seeks through timecodes. You can see a demo page to test it by yourself with FF browser.