Remove isWrapperOfType and toInnerGlobalObject

Instead of using isWrapperOfType and toInnerGlobalObject,
we can simply use toDOMWindow.

R=dcarney@chromium.org

Review URL: https://codereview.chromium.org/151203002

git-svn-id: svn://svn.chromium.org/blink/trunk@166193 bbb929c8-8fbe-4397-9dbb-9b2b20218538