WIP [esnext] implement async iteration proposal

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

Index: test/test262/local-tests/test/language/expressions/async-generators/early-errors-expression-yield-star-after-newline.js
diff --git a/test/test262/local-tests/test/language/expressions/async-generators/early-errors-expression-yield-star-after-newline.js b/test/test262/local-tests/test/language/expressions/async-generators/early-errors-expression-yield-star-after-newline.js
new file mode 100644
index 0000000000000000000000000000000000000000..2d2c83ab07ac066bd8ef575a51f043759bb6f8b3
--- /dev/null
+++ b/test/test262/local-tests/test/language/expressions/async-generators/early-errors-expression-yield-star-after-newline.js
@@ -0,0 +1,17 @@
+// 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: >
+  A newline may not precede the `*` token in a `yield` expression.
+negative:
+  phase: early
+  type: SyntaxError
+---*/
+
+(async function*() {
+  yield
+  * 1;
+});