bindings: Adds ASSERTs to check the creation context passed to public APIs.

      As a follow up of http://crrev.com/1166793006 , adds check if the creation
context passed to public API is the same as the global context.

BUG=497507

Review URL: https://codereview.chromium.org/1181943005

git-svn-id: svn://svn.chromium.org/blink/trunk@197105 bbb929c8-8fbe-4397-9dbb-9b2b20218538