Include wtf/RefCounted.h less often in modules/

With Oilpan enabled by default, tidy up #include use somewhat.

R=haraken@chromium.org
BUG=340522

Review URL: https://codereview.chromium.org/334263022

git-svn-id: svn://svn.chromium.org/blink/trunk@177014 bbb929c8-8fbe-4397-9dbb-9b2b20218538