Callback IDL types

[lukewarlow]

Random thought I had while cleaning up some work in WebKit, does it actually make sense for the callbacks to have their own IDL type per callback? Each callback type is identical but currently they're 3 different type defs. Is there any benefit to this? Should we just do CreateTrustedTypeCallback?

https://w3c.github.io/trusted-types/dist/spec/#trusted-type-policy-options

[annevk]

CreateScriptURLCallback has a different return type. But there's no reason for the other two to not be unified.