Remove deleted folder from base_unittests.isolate

TBR=maruel@chromium.org
NOTRY=True
BUG=


Review URL: https://chromiumcodereview.appspot.com/13668003

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@192813 0039d316-1c4b-4281-b951-d872f2087c98

base/base_unittests.isolate

@@ -27,7 +27,6 @@
         ],
         'isolate_dependency_untracked': [
           'data/',
-          'prefs/test/',
           'test/data/',
         ],
       },