fix(ext/web): ReadableStream.from() allows Iterable <Milly>

ext/web/06_streams.js

@@ -5088,28 +5088,32 @@ function initializeCountSizeFunction(globalObject) {
  WeakMapPrototypeSet(countSizeFunctionWeakMap, globalObject, size);
 }
 
-async function* createAsyncFromSyncIterator(syncIterator) {
- // deno-lint-ignore prefer-primordials
- yield* syncIterator;
-}
-
 // Ref: https://tc39.es/ecma262/#sec-getiterator
-function getIterator(obj, async = false) {
- if (async) {
- if (obj[SymbolAsyncIterator] == null) {
- if (obj[SymbolIterator] == null) {
- throw new TypeError("No iterator found");
- }
- return createAsyncFromSyncIterator(obj);
- } else {
- return obj[SymbolAsyncIterator]();
+function getAsyncOrSyncIterator(obj) {
+ let iterator;
+ if (obj[SymbolAsyncIterator] != null) {
+ iterator = obj[SymbolAsyncIterator]();
+ if (!isObject(iterator)) {
+ throw new TypeError(
+ "[Symbol.asyncIterator] returned a non-object value",
+ );
  }
- } else {
- if (obj[SymbolIterator] == null) {
- throw new TypeError("No iterator found");
+ } else if (obj[SymbolIterator] != null) {
+ iterator = obj[SymbolIterator]();
+ if (!isObject(iterator)) {
+ throw new TypeError("[Symbol.iterator] returned a non-object value");
  }
- return obj[SymbolIterator]();
+ } else {
+ throw new TypeError("No iterator found");
  }
+ if (typeof iterator.next !== "function") {
+ throw new TypeError("iterator.next is not a function");
+ }
+ return iterator;
+}
+
+function isObject(x) {
+ return (typeof x === "object" && x != null) || typeof x === "function";
 }
 
 const _resourceBacking = Symbol("[[resourceBacking]]");
@@ -5204,12 +5208,12 @@ class ReadableStream {
  );
  asyncIterable = webidl.converters.any(asyncIterable);
 
- const iterator = getIterator(asyncIterable, true);
+ const iterator = getAsyncOrSyncIterator(asyncIterable);
 
  const stream = createReadableStream(noop, async () => {
  // deno-lint-ignore prefer-primordials
  const res = await iterator.next();
- if (typeof res !== "object") {
+ if (!isObject(res)) {
  throw new TypeError("iterator.next value is not an object");
  }
  if (res.done) {
@@ -5218,12 +5222,12 @@ class ReadableStream {
  readableStreamDefaultControllerEnqueue(stream[_controller], res.value);
  }
  }, async (reason) => {
- if (typeof iterator.return === "undefined") {
+ if (iterator.return == null) {
  return undefined;
  } else {
  // deno-lint-ignore prefer-primordials
  const res = await iterator.return(reason);
- if (typeof res !== "object") {
+ if (!isObject(res)) {
  throw new TypeError("iterator.return value is not an object");
  } else {
  return undefined;