Bindings To-do:

- Add support for callbacks with non-void return types
- Add support for WebIDL namespaces
- Add support for generating name getters / setters / deleters
- Add support for generating index getters / setters with custom names
- Add support for maplike<> declarations
- Add support for setlike<> declarations
- Add support for Promise<> attributes
- Remove special casing of RegExp from overloading
- Add support for BufferType specialization in IDLTypes (currently implemented as IDLInterfaces)
- Stop invoking GetMethod(V, @@iterator) twice for sequence/FrozenArray disambiguation in overloading and union conversion
- Implement / verify FrozenArray reference semantics without [CachedAttribute]
- Add support for [SameObject]
- Add support for the remaining steps in the union conversion code
- Remove special casing of enums by passing context (attribute assignment, function parameter, dictionary assignment) to conversion functions
- Add better exception messages for all conversions
- Move all exception helpers out of JSDOMBindings.h and into its own header

Maybe:
- Split JSDOMConvert up into separate files per type