IE11 support broken for some streams

Created by: AxelDelmas

Math.trunc is not supported in IE11 so it breaks with some streams that use TimeSyncController: https://github.com/Dash-Industry-Forum/dash.js/blob/26fcf7e63f656e9cd02dc79723aec103076599f9/src/streaming/controllers/TimeSyncController.js#L334