No longer need to escape _includes

"includes" was added to the WebIDL grammar to avoid needing escaping:

https://heycam.github.io/webidl/#prod-OperationName

So we can drop the underscore and comments and simplify linking:

https://w3c.github.io/IndexedDB/#keyrange