[MSE] Spec updates published

I have posted more changes to the Media Source
Extensions<https://dvcs.w3.org/hg/html-media/raw-file/default/media-source/media-source.html>
 spec.

Summary of changes:
Bug 21112 <https://www.w3.org/Bugs/Public/show_bug.cgi?id=21112> - Add
appendWindowStart & appendWindowEnd attributes.
Bug 19676 <https://www.w3.org/Bugs/Public/show_bug.cgi?id=19676> - Clarify
overlapped frame definitions and splice logic.
Bug 21172 <https://www.w3.org/Bugs/Public/show_bug.cgi?id=21172> - Added
coded frame removal and eviction algorithms.

Diffs:
https://dvcs.w3.org/hg/html-media/rev/f0fb58d45f96

Aaron