fix(cli/web/fetch): Make Response constructor standard

cli/js/lib.deno.shared_globals.d.ts

@@ -922,6 +922,12 @@ declare const Request: {
   new (input: RequestInfo, init?: RequestInit): Request;
 };
 
+interface ResponseInit {
+  headers?: HeadersInit;
+  status?: number;
+  statusText?: string;
+}
+
 type ResponseType =
   | "basic"
   | "cors"
@@ -945,20 +951,7 @@ interface Response extends Body {
 
 declare const Response: {
   prototype: Response;
-
-  // TODO(#4667) Response constructor is non-standard.
-  // new(body?: BodyInit | null, init?: ResponseInit): Response;
-  new (
-    url: string,
-    status: number,
-    statusText: string,
-    headersList: Array<[string, string]>,
-    rid: number,
-    redirected_: boolean,
-    type_?: null | ResponseType,
-    body_?: null | Body
-  ): Response;
-
+  new (body?: BodyInit | null, init?: ResponseInit): Response;
   error(): Response;
   redirect(url: string, status?: number): Response;
 };

cli/js/web/body.ts

@@ -7,15 +7,7 @@ import { ReadableStreamImpl } from "./streams/readable_stream.ts";
 const { TextEncoder, TextDecoder } = encoding;
 const DenoBlob = blob.DenoBlob;
 
-export type BodySource =
-  | Blob
-  | BufferSource
-  | FormData
-  | URLSearchParams
-  | ReadableStream
-  | string;
-
-function validateBodyType(owner: Body, bodySource: BodySource): boolean {
+function validateBodyType(owner: Body, bodySource: BodyInit | null): boolean {
   if (
     bodySource instanceof Int8Array ||
     bodySource instanceof Int16Array ||
@@ -75,6 +67,8 @@ function bufferFromStream(stream: ReadableStreamReader): Promise<ArrayBuffer> {
             parts.push(encoder.encode(value));
           } else if (value instanceof ArrayBuffer) {
             parts.push(new Uint8Array(value));
+          } else if (value instanceof Uint8Array) {
+            parts.push(value);
           } else if (!value) {
             // noop for undefined
           } else {
@@ -113,7 +107,10 @@ export const BodyUsedError =
 export class Body implements domTypes.Body {
   protected _stream: ReadableStreamImpl<string | ArrayBuffer> | null;
 
-  constructor(protected _bodySource: BodySource, readonly contentType: string) {
+  constructor(
+    protected _bodySource: BodyInit | null,
+    readonly contentType: string
+  ) {
     validateBodyType(this, _bodySource);
     this._bodySource = _bodySource;
     this.contentType = contentType;
@@ -149,7 +146,9 @@ export class Body implements domTypes.Body {
   }
 
   public async blob(): Promise<Blob> {
-    return new DenoBlob([await this.arrayBuffer()]);
+    return new DenoBlob([await this.arrayBuffer()], {
+      type: this.contentType,
+    });
   }
 
   // ref: https://fetch.spec.whatwg.org/#body-mixin

cli/js/web/dom_types.d.ts

@@ -305,7 +305,6 @@ export interface Response extends Body {
   readonly redirected: boolean;
   readonly status: number;
   readonly statusText: string;
-  readonly trailer: Promise<Headers>;
   readonly type: ResponseType;
   readonly url: string;
   clone(): Response;