Style: 'RefPtr<...>* = 0' is a valid parameter.

We accept 'RefPtr<...>*' but not 'RefPtr<...>* = 0' in a function's
parameter list. This patch changes the style checker to accept both.

R=levin@chromium.org

Review URL: https://codereview.chromium.org/22334005

git-svn-id: svn://svn.chromium.org/blink/trunk@155750 bbb929c8-8fbe-4397-9dbb-9b2b20218538