Using URL as map keys is problematic without defining equality

[annevk]

What is the issue with the HTML Standard?

Several possible ways forward here:

1. We always serialize URLs before using them as keys. I suspect in pretty much all cases we want URL serialized equality.
2. We define a way to define map key equality and use that here (or alternatively define somewhere in the URL Standard that when a URL is used as a key in a map, the map key equality algorithm is the URL equals algorithm).
3. We say alongside each map how the keys are compared in prose, without anything formal.

I think I like 2 best, as it also suggests a way forward on how to resolve similar issues elsewhere. But I don't feel strongly.