Should `includes` be allowed as operation names?

[saschanaz]

includes has been a reserved keyword since we introduced mixins, but IndexedDB is using that word for an operation: w3c/IndexedDB@98b28b9

[Exposed=(Window,Worker)]
interface IDBKeyRange {
  // -- snip --

  boolean _includes(any key);
};

@bzbarsky raised a concern that we shouldn't force escaping here. What do you think?

[bzbarsky]

We should generally not make backwards-incompatible changes unless we're forced to. So yes. ideally we would keep allowing "includes" as an identifier-like thing in all the cases that are unambiguous.

[inexorabletash]

It'd let me remove a note from the spec explaining that _includes is just the IDL, not the actual method name. So 👍 as a spec author, not sure how much work updating the blink implementation would be.

Would want WPT and Bikeshed updates too.