Use RelocInfo::IsNone in a few more places.

I had missed some earlier.

Followup to:
https://chromiumcodereview.appspot.com/11695006/

There are now NONE and NONE64 RelocInfo types, but only ARM uses them
both at the same time. They were added in:
https://chromiumcodereview.appspot.com/11191029/

R= ulan@chromium.org

Review URL: https://chromiumcodereview.appspot.com/11742045
Patch from JF Bastien <jfb@chromium.org>.

git-svn-id: https://v8.googlecode.com/svn/branches/bleeding_edge@13317 ce2b1a6d-e550-0410-aec6-3dcde31c8c00