String.prototype.matchAll: add tests for stage 3

`RegExp.prototype[Symbol.matchAll]`: Add basic tests.

test/built-ins/RegExp/prototype/Symbol.matchAll/coerce-arg.js

+// Copyright (C) 2018 Jordan Harband. All rights reserved.
+// This code is governed by the BSD license found in the LICENSE file.
+
+/*---
+description: String coercion of string parameter
+info: |
+    RegExp.prototype [ @@matchAll ] ( string )
+
+    [...]
+    2. Let S be ? ToString(O).
+    [...]
+features: [Symbol.match, Symbol.matchAll]
+---*/
+
+var obj = {
+  valueOf: function() {
+    $ERROR('This method should not be invoked.');
+  },
+  toString: function() {
+    throw new Test262Error('toString invoked');
+  }
+};
+obj[Symbol.match] = true;
+
+assert.throws(Test262Error, function () {
+  /toString value/[Symbol.matchAll](obj);
+});

test/built-ins/RegExp/prototype/Symbol.matchAll/get-species-constructor-err.js

+// Copyright (C) 2015 the V8 project authors. All rights reserved.
+// This code is governed by the BSD license found in the LICENSE file.
+
+/*---
+description: >
+    Behavior when error is thrown during retrieval of `Symbol.species` property
+info: |
+    3. Let C be ? SpeciesConstructor(R, %RegExp%).
+features: [Symbol.match, Symbol.matchAll, Symbol.species]
+---*/
+
+var obj = {};
+Object.defineProperty(obj, Symbol.species, {
+  get: function () {
+    throw new Test262Error();
+  }
+});
+obj[Symbol.match] = true;
+
+assert.throws(Test262Error, function() {
+  RegExp.prototype[Symbol.matchAll].call(obj);
+});

test/built-ins/RegExp/prototype/Symbol.matchAll/length.js

+// Copyright (C) 2018 Jordan Harband. All rights reserved.
+// This code is governed by the BSD license found in the LICENSE file.
+/*---
+description: RegExp.prototype[Symbol.matchAll] `length` property
+info: |
+    ES6 Section 17:
+    Every built-in Function object, including constructors, has a length
+    property whose value is an integer. Unless otherwise specified, this value
+    is equal to the largest number of named arguments shown in the subclause
+    headings for the function description, including optional parameters.
+
+    [...]
+
+    Unless otherwise specified, the length property of a built-in Function
+    object has the attributes { [[Writable]]: false, [[Enumerable]]: false,
+    [[Configurable]]: true }.
+includes: [propertyHelper.js]
+features: [Symbol.matchAll]
+---*/
+
+assert.sameValue(RegExp.prototype[Symbol.matchAll].length, 1);
+
+verifyNotEnumerable(RegExp.prototype[Symbol.matchAll], 'length');
+verifyNotWritable(RegExp.prototype[Symbol.matchAll], 'length');
+verifyConfigurable(RegExp.prototype[Symbol.matchAll], 'length');

test/built-ins/RegExp/prototype/Symbol.matchAll/name.js

+// Copyright (C) 2018 Jordan Harband. All rights reserved.
+// This code is governed by the BSD license found in the LICENSE file.
+/*---
+description: RegExp.prototype[Symbol.matchAll] `name` property
+info: |
+    The value of the name property of this function is "[Symbol.matchAll]".
+
+    ES6 Section 17:
+
+    [...]
+
+    Unless otherwise specified, the name property of a built-in Function
+    object, if it exists, has the attributes { [[Writable]]: false,
+    [[Enumerable]]: false, [[Configurable]]: true }.
+includes: [propertyHelper.js]
+features: [Symbol.matchAll]
+---*/
+
+assert.sameValue(RegExp.prototype[Symbol.matchAll].name, '[Symbol.matchAll]');
+
+verifyNotEnumerable(RegExp.prototype[Symbol.matchAll], 'name');
+verifyNotWritable(RegExp.prototype[Symbol.matchAll], 'name');
+verifyConfigurable(RegExp.prototype[Symbol.matchAll], 'name');

test/built-ins/RegExp/prototype/Symbol.matchAll/prop-desc.js

+// Copyright (C) 2018 Jordan Harband. All rights reserved.
+// This code is governed by the BSD license found in the LICENSE file.
+
+/*---
+description: RegExp.prototype[Symbol.matchAll] property descriptor
+info: |
+    ES6 Section 17
+
+    Every other data property described in clauses 18 through 26 and in Annex
+    B.2 has the attributes { [[Writable]]: true, [[Enumerable]]: false,
+    [[Configurable]]: true } unless otherwise specified.
+includes: [propertyHelper.js]
+features: [Symbol.matchAll]
+---*/
+
+assert.sameValue(typeof RegExp.prototype[Symbol.matchAll], 'function');
+verifyNotEnumerable(RegExp.prototype, Symbol.matchAll);
+verifyWritable(RegExp.prototype, Symbol.matchAll);
+verifyConfigurable(RegExp.prototype, Symbol.matchAll);

test/built-ins/RegExp/prototype/Symbol.matchAll/this-val-non-obj.js

+// Copyright (C) 2018 Jordan Harband. All rights reserved.
+// This code is governed by the BSD license found in the LICENSE file.
+
+/*---
+description: The `this` value must be an object
+info: |
+    1. Let R be the this value.
+    2. Return ? MatchAllIterator(R, string).
+    [...]
+    1. If ? IsRegExp(R) is not true, throw a TypeError exception.
+features: [Symbol.matchAll]
+---*/
+
+assert.throws(TypeError, function() {
+  RegExp.prototype[Symbol.matchAll].call(undefined);
+});
+
+assert.throws(TypeError, function() {
+  RegExp.prototype[Symbol.matchAll].call(null);
+});
+
+assert.throws(TypeError, function() {
+  RegExp.prototype[Symbol.matchAll].call(true);
+});
+
+assert.throws(TypeError, function() {
+  RegExp.prototype[Symbol.matchAll].call('string');
+});
+
+assert.throws(TypeError, function() {
+  RegExp.prototype[Symbol.matchAll].call(Symbol.matchAll);
+});
+
+assert.throws(TypeError, function() {
+  RegExp.prototype[Symbol.matchAll].call(86);
+});

test/built-ins/RegExp/prototype/Symbol.matchAll/this-val-non-regexp.js

+// Copyright (C) 2018 Jordan Harband. All rights reserved.
+// This code is governed by the BSD license found in the LICENSE file.
+
+/*---
+description: The `this` value must be a regular expression (has Symbol.match)
+info: |
+    1. Let R be the this value.
+    2. Return ? MatchAllIterator(R, string).
+    [...]
+    1. If ? IsRegExp(R) is not true, throw a TypeError exception.
+features: [Symbol.match, Symbol.matchAll]
+---*/
+
+var regexObj = {};
+regexObj[Symbol.match] = true;
+var obj = {};
+
+RegExp.prototype[Symbol.matchAll].call(regexObj);
+
+assert.throws(TypeError, function() {
+  RegExp.prototype[Symbol.matchAll].call(obj);
+});