Emit enums as union types instead of current string

[saschanaz]

Fixes #200

Current:

interface Request extends Object, Body {
    readonly cache: string;
    readonly credentials: string;
    readonly destination: string;
    readonly headers: Headers;
    readonly integrity: string;
    readonly keepalive: boolean;
    readonly method: string;
    readonly mode: string;
    readonly redirect: string;
    readonly referrer: string;
    readonly referrerPolicy: string;
    readonly type: string;
    readonly url: string;
    clone(): Request;
}

Fixed:

interface Request extends Object, Body {
    readonly cache: RequestCache;
    readonly credentials: RequestCredentials;
    readonly destination: RequestDestination;
    readonly headers: Headers;
    readonly integrity: string;
    readonly keepalive: boolean;
    readonly method: string;
    readonly mode: RequestMode;
    readonly redirect: RequestRedirect;
    readonly referrer: string;
    readonly referrerPolicy: ReferrerPolicy;
    readonly type: RequestType;
    readonly url: string;
    clone(): Request;
}

type ReferrerPolicy = "" | "no-referrer" | "no-referrer-when-downgrade" | "origin-only" | "origin-when-cross-origin" | "unsafe-url";
type RequestCache = "default" | "no-store" | "reload" | "no-cache" | "force-cache";
type RequestCredentials = "omit" | "same-origin" | "include";
type RequestDestination = "" | "document" | "sharedworker" | "subresource" | "unknown" | "worker";
type RequestMode = "navigate" | "same-origin" | "no-cors" | "cors";
type RequestRedirect = "follow" | "error" | "manual";
type RequestType = "" | "audio" | "font" | "image" | "script" | "style" | "track" | "video";

[saschanaz]

Will reopen after fixing build.

[mhegazy]

@zhengbli can you please review this change?

[zhengbli]

LGTM

[zhengbli]

Thanks @saschanaz !

[mhegazy]

We need to document this as a breaking change.