Add a test for GetIterator(obj, ~async~) attempting to call obj[@@asyncIterator] even if that value is an object with an [[IsHTMLDDA]] internal slot.

test/annexB/language/statements/for-await-of/iterator-close-return-emulates-undefined-throws-when-called.js

@@ -0,0 +1,34 @@
+// Copyright (C) 2017 Mozilla Corporation. All rights reserved.
+// This code is governed by the BSD license found in the LICENSE file.
+
+/*---
+esid: sec-getiterator
+description: >
+    `GetIterator(obj, ~async~)` must attempt to call `obj[@@asyncIterator]` when
+    that value is an object with an [[IsHTMLDDA]] internal slot, not act as if
+    the value were `undefined`.
+features: [async-iteration, uncallableAndIsHTMLDDA]
+flags: [async]
+---*/
+
+async function f() {
+  var fakeIter = {
+    [Symbol.asyncIterator]: $262.uncallableAndIsHTMLDDA(),
+    get [Symbol.iterator]() {
+      throw new Test262Error("shouldn't touch Symbol.iterator");
+    },
+  };
+
+  for await (var x of fakeIter)
+    return "for-await-of body shouldn't be reached";
+
+  return "should have failed earlier";
+}
+
+f().then($DONE,
+         function (e) {
+           assert.sameValue(e.constructor, TypeError,
+                            "expeted TypeError from calling " +
+                            "uncallableAndIsHTMLDDA() value");
+         })
+   .then($DONE, $DONE);