Revert 234034 "Disabled ppapi browsertests for TCPSocket due to ..."

Fix has landed. Reenable the tests.

> Disabled ppapi browsertests for TCPSocket due to flakiness.
> 
> BUG=316933

TBR=scheib@chromium.org

Review URL: https://codereview.chromium.org/61693006

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@236058 0039d316-1c4b-4281-b951-d872f2087c98
SVN changes up to revision 236058