Editorial: Link fixes/simplifications (#395)

* Editorial: Link fixes/simplifications

* Add link-defaults entry for "event" (use DOM's)
* Add a "for" for the ECMAScript anchors, use it to disambiguate.
* Drop anchor for DOM's Document (no longer needed)
* Drop anchor for ECMAScript's TypeError - use IDL's interface instead
* Turn on "Assume Explicit For" - yay!

Author: inexorabletash