WebIDL parser could return null in the set of external dependencies
WebIDL parser could return null in the set of external dependencies

The code that handled "maplike" and other iterables incorrectly went one level
too deep before it called "parseType" and thus did not parse IDL definitions
such as this one from the WebRTC spec:

interface RTCStatsReport { readonly maplike<DOMString, object>; };

Similarly, for some reason, webidl2.js sometimes return IDL array types that
directly link to the underlying type string instead of to an IDL construct that
describes the underlying type. Typically happened for IDL definitions such as
this one from the Presentation API spec:

[Constructor(DOMString[] urls)] interface PresentationRequest {};

(That could be a bug in webidl2.js, actually)

The parseType function now creates a fake IDL construct if it receives a string
as parameter.

tidoust/reffy,tidoust/reffy