Support Records

[niloc132]

`@JsProperty on record components behave slightly differently than one would naively expect:

• the generated accessor method should be treated as if it was a "getter", despite not having that name
• the private final field should not be annotated/exposed at all

@JsType on a record should expose the constructor and the methods as @JsMethod, but components should not be treated as if they were annotated with anything.