Removing the  --disable-sctp-data-channels flag
This has been enabled by default for several releases.

BUG=351298

Review URL: https://codereview.chromium.org/195113003

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@256820 0039d316-1c4b-4281-b951-d872f2087c98
SVN changes up to revision 256820