[MSE] Spec updates published

Hi,

More updates to the Media Source
Extensions<http://dvcs.w3.org/hg/html-media/raw-file/tip/media-source/media-source.html>spec
have been published.

Summary of changes:
Editorial fixes:
- Fixed a bunch if missing "the"s.

Bug 18576 <https://www.w3.org/Bugs/Public/show_bug.cgi?id=18576>
- Added a step to the beginning of the duration change algorithm to abort if
  the new duration is the same as the existing duration.

Bug 18579 <https://www.w3.org/Bugs/Public/show_bug.cgi?id=18579>
- Created MediaSource object URL definition.
- Added URL Object section with IDL & createObjectURL() algorithm.

Bug 18550 <https://www.w3.org/Bugs/Public/show_bug.cgi?id=18550>
- Added Track ID and Track description definitions & updated text to
reference
  these definitions.

Bug 18573 <https://www.w3.org/Bugs/Public/show_bug.cgi?id=18573>
- Reworded start overlap text for audio frames & included crosslapping as
an option.

Bug 18655 <https://www.w3.org/Bugs/Public/show_bug.cgi?id=18655>
- Removed rendering of silence requirement from Section 2.5.


Diffs: http://dvcs.w3.org/hg/html-media/rev/ca093bbbbefb