check-webkit-style: Allow >> for templates.

check-webkit-style should accept >> for templates [1]. It showed an error
because operator>> needs spaces around it.

[1] http://chromium-cpp.appspot.com/

BUG=

Review URL: https://codereview.chromium.org/618993002

git-svn-id: svn://svn.chromium.org/blink/trunk@183028 bbb929c8-8fbe-4397-9dbb-9b2b20218538