`any` type conversion does not take into account of symbols

[TimothyGu]

https://heycam.github.io/webidl/#es-any uses Type(x), but does not define a case for when Type(V) is Symbol, as is possible under the current ES spec.

[bzbarsky]

Yeah, we probably need to define an IDL type for Symbols and map to that...

[TimothyGu]

@bzbarsky, do we really need a symbol type for IDL though? What applications for it can you foresee?

[bzbarsky]

None offhand, but the way IDL works in general is that ES types get mapped to IDL types, so we need a way to represent Symbol on the IDL side. The Symbol type would work much like "object": it would just be an opaque reference to the ES Symbol.

There would be no syntactic way to express the Symbol type other than "any".