bindings: Adds refObject to WrapperTypeInfo.

Adds refObejct to WrapperTypeInfo in addition to derefObject, so that we can call ref() function without knowing type T nor V8T.

BUG=235436

Review URL: https://codereview.chromium.org/505733002

git-svn-id: svn://svn.chromium.org/blink/trunk@180849 bbb929c8-8fbe-4397-9dbb-9b2b20218538