Added a very complicated AsyncIterableReader class.

The class was already implemented in
"https://deno.land/std@0.144.0/streams/conversion.ts".  So, I litterally
lost 1 day of work!  I hate myself.

vendor/deno.land/std@0.188.0/streams/reader_from_stream_reader.ts

@@ -0,0 +1,43 @@
+// Copyright 2018-2023 the Deno authors. All rights reserved. MIT license.
+// This module is browser compatible.
+
+import { Buffer } from "../io/buffer.ts";
+import { writeAll } from "./write_all.ts";
+import type { Reader } from "../types.d.ts";
+
+/**
+ * Create a `Reader` from a `ReadableStreamDefaultReader`.
+ *
+ * @example
+ * ```ts
+ * import { copy } from "https://deno.land/std@$STD_VERSION/streams/copy.ts";
+ * import { readerFromStreamReader } from "https://deno.land/std@$STD_VERSION/streams/reader_from_stream_reader.ts";
+ *
+ * const res = await fetch("https://deno.land");
+ * const file = await Deno.open("./deno.land.html", { create: true, write: true });
+ *
+ * const reader = readerFromStreamReader(res.body!.getReader());
+ * await copy(reader, file);
+ * file.close();
+ * ```
+ */
+export function readerFromStreamReader(
+  streamReader: ReadableStreamDefaultReader<Uint8Array>,
+): Reader {
+  const buffer = new Buffer();
+
+  return {
+    async read(p: Uint8Array): Promise<number | null> {
+      if (buffer.empty()) {
+        const res = await streamReader.read();
+        if (res.done) {
+          return null; // EOF
+        }
+
+        await writeAll(buffer, res.value);
+      }
+
+      return buffer.read(p);
+    },
+  };
+}