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@0.144.0/_util/assert.ts

@@ -0,0 +1,16 @@
+// Copyright 2018-2022 the Deno authors. All rights reserved. MIT license.
+// This module is browser compatible.
+
+export class DenoStdInternalError extends Error {
+  constructor(message: string) {
+    super(message);
+    this.name = "DenoStdInternalError";
+  }
+}
+
+/** Make an assertion, if not `true`, then throw. */
+export function assert(expr: unknown, msg = ""): asserts expr {
+  if (!expr) {
+    throw new DenoStdInternalError(msg);
+  }
+}