Which WebIDL types are maps? about infra

[domenic]

I'll try to tackle this and #14 within the next day or so, along the lines of the strategy of

Maybe what we want to do here is state something like "often we use lists in a place that expects sequences, or treat sequences like lists. This kind of implicit conversion is OK, as long as the type systems match up."

However, as noted in #61, I think probably such Web IDL-specific stuff should get moved into Web IDL.

[jyasskin]

We may want to explicitly disallow objects, because of the ambiguities around own vs inherited properties. Dictionaries and records have unambiguous contents and ordering.

[domenic]

Closed by whatwg/webidl@26aa830 (I got the commit message wrong)