WIP [esnext] implement async iteration proposal

test/test262/local-tests/test/language/expressions/async-generators/expression-yield-star-before-newline.js

Index: test/test262/local-tests/test/language/expressions/async-generators/expression-yield-star-before-newline.js
diff --git a/test/test262/local-tests/test/language/expressions/async-generators/expression-yield-star-before-newline.js b/test/test262/local-tests/test/language/expressions/async-generators/expression-yield-star-before-newline.js
new file mode 100644
index 0000000000000000000000000000000000000000..d22ef2f88f8a9a247028913e9d55dcc90ea4051c
--- /dev/null
+++ b/test/test262/local-tests/test/language/expressions/async-generators/expression-yield-star-before-newline.js
@@ -0,0 +1,20 @@
+// Copyright 2017 the V8 project authors. All rights reserved.
+// This code is governed by the BSD license found in the LICENSE file.
+
+/*---
+author: Caitlin Potter <caitp@igalia.com>
+esid: 14.4
+description: >
+  The right-hand side of a `yield *` expression may appear on a new line.
+flags: [async]
+---*/
+
+var g = async function*() {};
+
+(async function*() {
+  yield*
+  g();
+})().next().then(function(result) {
+  assert.sameValue(result.value, undefined);
+  assert.sameValue(result.done, true);
+}).then($DONE, $DONE);