Docserver: assertIn(foo, bar) --> assertTrue(foo in bar) for compatibility.

TBR=jyasskin@chromium.org

Review URL: https://codereview.chromium.org/25103004

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@225766 0039d316-1c4b-4281-b951-d872f2087c98
SVN changes up to revision 225766