Minimum viable ReadableStream.

No methods or attributes are mapped (yet).

This is mostly useful for constructing a `Response` from another one's
body in a streaming fashion.

crates/web-sys/Cargo.toml

@@ -782,6 +782,7 @@ RadioNodeList = []
 Range = []
 RcwnPerfStats = []
 RcwnStatus = []
+ReadableStream = []
 RecordingState = []
 ReferrerPolicy = []
 RegisterRequest = []

crates/web-sys/tests/wasm/response.rs

@@ -34,3 +34,13 @@ async fn test_response_from_bytes() {
         assert_eq!(&data_view.get_uint8(i), byte);
     }
 }
+
+#[wasm_bindgen_test]
+async fn test_response_from_other_body() {
+    let input = "Hello, world!";
+    let response_a = Response::new_with_opt_str(Some(input)).unwrap();
+    let body = response_a.body();
+    let response_b = Response::new_with_opt_readable_stream(body.as_ref()).unwrap();
+    let output = JsFuture::from(response_b.text().unwrap()).await.unwrap();
+    assert_eq!(JsValue::from_str(input), output);
+}

crates/web-sys/webidls/enabled/Fetch.webidl

@@ -8,7 +8,7 @@
  */
 
 typedef object JSON;
-typedef (Blob or BufferSource or FormData or URLSearchParams or USVString) BodyInit;
+typedef (Blob or BufferSource or FormData or URLSearchParams or USVString or ReadableStream) BodyInit;
 
 [Exposed=(Window,Worker)]
 interface mixin Body {
@@ -23,6 +23,7 @@ interface mixin Body {
   Promise<JSON> json();
   [Throws]
   Promise<USVString> text();
+  readonly attribute ReadableStream? body;
 };
 
 // These are helper dictionaries for the parsing of a

crates/web-sys/webidls/enabled/ReadableStream.webidl

@@ -0,0 +1,10 @@
+/* -*- Mode: IDL; tab-width: 2; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this file,
+ * You can obtain one at http://mozilla.org/MPL/2.0/.
+ */
+
+// Minimum viable ReadableStream, for use by other objects.
+[Exposed=(Window,Worker)]
+interface ReadableStream {
+};

crates/web-sys/webidls/enabled/Response.webidl

@@ -7,9 +7,7 @@
  * https://fetch.spec.whatwg.org/#response-class
  */
 
-// This should be Constructor(optional BodyInit... but BodyInit doesn't include
-// ReadableStream yet because we don't want to expose Streams API to Request.
-[Constructor(optional (Blob or BufferSource or FormData or URLSearchParams or ReadableStream or USVString)? body, optional ResponseInit init),
+[Constructor(optional BodyInit? body, optional ResponseInit init),
  Exposed=(Window,Worker)]
 interface Response {
   [NewObject] static Response error();
@@ -32,13 +30,6 @@ interface Response {
 };
 Response includes Body;
 
-// This should be part of Body but we don't want to expose body to request yet.
-// See bug 1387483.
-partial interface Response {
-  [GetterThrows, Func="mozilla::dom::DOMPrefs::StreamsEnabled"]
-  readonly attribute ReadableStream? body;
-};
-
 dictionary ResponseInit {
   unsigned short status = 200;
   ByteString statusText = "OK";