Unify WrapperTypeInfo and gin::WrapperType

BUG=321631
R=abarth@chromium.org,dcarney@chromium.org

Review URL: https://codereview.chromium.org/77453003

git-svn-id: svn://svn.chromium.org/blink/trunk@162467 bbb929c8-8fbe-4397-9dbb-9b2b20218538