Export getMaxSegmentDuration() on presentationTimeline.
Export getMaxSegmentDuration() on presentationTimeline.

Closes #2124.

Change-Id: I6260c2156575ff5adf5c251713d0e1a522334251

tvoli/shaka-player,shaka-project/shaka-player,shaka-project/shaka-player,tvoli/shaka-player,shaka-project/shaka-player,tvoli/shaka-player,tvoli/shaka-player,shaka-project/shaka-player