bindings: Removes unnecessary Event-related code.

Removes unused ModuleProxy, EventInterfaces.h, etc.

BUG=235436

Review URL: https://codereview.chromium.org/551003002

git-svn-id: svn://svn.chromium.org/blink/trunk@181657 bbb929c8-8fbe-4397-9dbb-9b2b20218538