Declaring constructors as methods is strange

[domenic]

In https://privacycg.github.io/saa-non-cookie-storage/#storageaccesshandle the members BroadcastChannel and SharedWorker are presumably supposed to be sort of namespaced versions of the global BroadcastChannel and SharedWorker constructors.

However, since they are declared as Web IDL operations, they end up as JavaScript methods, not constructors.

This has several observable differences, notably around how they don't require new, and fail various IsConstructor tests. E.g. they cannot be subclassed.

Ideally we would define these as constructors. Doing so would probably require new Web IDL infrastructure, however...