Add basic coverage for Symbol.asyncIterator

test/built-ins/Symbol/asyncIterator/cross-realm.js

@@ -0,0 +1,15 @@
+// Copyright (C) 2018 Leo Balter. All rights reserved.
+// This code is governed by the BSD license found in the LICENSE file.
+
+/*---
+esid: sec-symbol.asynciterator
+description: Value shared by all realms
+info: |
+  Unless otherwise specified, well-known symbols values are shared by all
+  realms.
+features: [cross-realm, Symbol.asyncIterator]
+---*/
+
+var OSymbol = $262.createRealm().global.Symbol;
+
+assert.sameValue(Symbol.asyncIterator, OSymbol.asyncIterator);

test/built-ins/Symbol/asyncIterator/prop-desc.js

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+// Copyright (C) 2018 Leo Balter. All rights reserved.
+// This code is governed by the BSD license found in the LICENSE file.
+
+/*---
+esid: sec-symbol.asynciterator
+description: >
+    `Symbol.asyncIterator` property descriptor
+info: |
+    This property has the attributes { [[Writable]]: false, [[Enumerable]]:
+    false, [[Configurable]]: false }.
+includes: [propertyHelper.js]
+features: [Symbol.asyncIterator]
+---*/
+
+assert.sameValue(typeof Symbol.asyncIterator, 'symbol');
+
+verifyProperty(Symbol, 'asyncIterator', {
+    enumerable: false,
+    writable: false,
+    configurable: false,
+});