Add missing dependency from mojo_js_bindings_unittests to mojom_test

BUG=none
R=abarth@chromium.org

Review URL: https://codereview.chromium.org/83153002

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@236750 0039d316-1c4b-4281-b951-d872f2087c98
SVN changes up to revision 236750