Sync the documentation of seekable() with the MediaSource specification

https://www.w3.org/Bugs/Public/show_bug.cgi?id=27296

Also tweak an assert to match the preceding comment.

BUG=432051
R=henriks@opera.com

Review URL: https://codereview.chromium.org/733453002

git-svn-id: svn://svn.chromium.org/blink/trunk@185799 bbb929c8-8fbe-4397-9dbb-9b2b20218538
2 files changed
tree: 71be6737b7e9018a8b47feb9629b64c8a535becb
  1. third_party/