Refactor tests for built-in @@iterator methods

Assert the value of the properties and update the test frontmatter to
include the `Symbol.iterator` feature.

test/built-ins/Array/prototype/Symbol.iterator/property-descriptor.js → test/built-ins/Array/prototype/Symbol.iterator.js

@@ -2,13 +2,19 @@
 // This code is governed by the BSD license found in the LICENSE file.
 
 /*---
-  description: >
-      The method should exist on the Array prototype, and it should be writable
-      and configurable, but not enumerable.
-  includes: [propertyHelper.js]
-  es6id: 22.1.3.4
- ---*/
+description: Initial state of the Symbol.iterator property
+info: >
+    The initial value of the @@iterator property is the same function object as
+    the initial value of the Array.prototype.values property.
 
+    Per ES6 section 17, the method should exist on the Array prototype, and it
+    should be writable and configurable, but not enumerable.
+includes: [propertyHelper.js]
+features: [Symbol.iterator]
+es6id: 22.1.3.30
+---*/
+
+assert.sameValue(Array.prototype[Symbol.iterator], Array.prototype.values);
 verifyNotEnumerable(Array.prototype, Symbol.iterator);
 verifyWritable(Array.prototype, Symbol.iterator);
 verifyConfigurable(Array.prototype, Symbol.iterator);

test/built-ins/Map/prototype/Symbol.iterator-property-descriptor.js → test/built-ins/Map/prototype/Symbol.iterator.js

@@ -2,12 +2,17 @@
 // This code is governed by the BSD license found in the LICENSE file.
 
 /*---
-  description: >
-      The method should exist on the Map prototype, and it should be writable
-      and configurable, but not enumerable.
-  includes: [propertyHelper.js]
-  es6id: 23.1.3.12
- ---*/
+description: Initial state of the Symbol.iterator property
+info: >
+    The initial value of the @@iterator property is the same function object as
+    the initial value of the entries property.
+
+    Per ES6 section 17, the method should exist on the Array prototype, and it
+    should be writable and configurable, but not enumerable.
+includes: [propertyHelper.js]
+features: [Symbol.iterator]
+es6id: 23.1.3.12
+---*/
 
 verifyNotEnumerable(Map.prototype, Symbol.iterator);
 verifyWritable(Map.prototype, Symbol.iterator);

test/built-ins/Set/prototype/Symbol.iterator/property-descriptor.js → test/built-ins/Set/prototype/Symbol.iterator.js

@@ -2,13 +2,19 @@
 // This code is governed by the BSD license found in the LICENSE file.
 
 /*---
-  description: >
-      The method should exist on the Array prototype, and it should be writable
-      and configurable, but not enumerable.
-  includes: [propertyHelper.js]
-  es6id: 23.2.3.11
- ---*/
+description: Initial state of the Symbol.iterator property
+info: >
+    The initial value of the @@iterator property is the same function object as
+    the initial value of the values property.
 
+    Per ES6 section 17, the method should exist on the Set prototype, and it
+    should be writable and configurable, but not enumerable.
+includes: [propertyHelper.js]
+features: [Symbol.iterator]
+es6id: 23.2.3.11
+---*/
+
+assert.sameValue(Set.prototype[Symbol.iterator], Set.prototype.values);
 verifyNotEnumerable(Set.prototype, Symbol.iterator);
 verifyWritable(Set.prototype, Symbol.iterator);
 verifyConfigurable(Set.prototype, Symbol.iterator);

test/language/arguments-object/mapped/Symbol.iterator/property-descriptor.js → test/language/arguments-object/mapped/Symbol.iterator.js

@@ -7,6 +7,7 @@ description: >
     protocol.
 includes: [propertyHelper.js]
 flags: [noStrict]
+features: [Symbol.iterator]
 ---*/
 
 (function() {

test/language/arguments-object/unmapped/Symbol.iterator/property-descriptor.js → test/language/arguments-object/unmapped/Symbol.iterator.js

@@ -7,6 +7,7 @@ description: >
     protocol.
 includes: [propertyHelper.js]
 flags: [noStrict]
+features: [Symbol.iterator]
 ---*/
 
 (function() {