Annotate tests with required features

test/language/statements/for-of/generator.js

@@ -4,6 +4,7 @@
 es6id: 13.6.4.13
 description: >
     Generator function should return valid iterable objects.
+features: [generators]
 ---*/
 
 function* values() {

test/language/statements/for-of/generic-iterable.js

@@ -4,6 +4,7 @@
 es6id: 13.6.4.13
 description: >
     Generic objects with `@@iterator` protocols should function as iterables.
+features: [Symbol.iterator]
 ---*/
 
 var iterable = {};

test/language/statements/for-of/iterator-as-proxy.js

@@ -5,6 +5,7 @@ es6id: 13.6.4.13
 description: >
     Iterators that are implemented as proxies should behave identically to
     non-proxy versions.
+features: [Proxy, Symbol.iterator]
 ---*/
 
 var iterable = {};

test/language/statements/for-of/iterator-next-reference.js

@@ -5,6 +5,7 @@ es6id: 13.6.4.13 S5.c
 description: >
     The iterator's `next` method should be accessed with each iteration as per
     the `IteratorStep` abstract operation (7.4.5).
+features: [Symbol.iterator]
 ---*/
 
 var iterable = {};

test/language/statements/for-of/iterator-next-result-done-attr.js

@@ -5,6 +5,7 @@ es6id: 7.4.3
 description: >
     The `done` value of iteration result objects should be interpreted as
     incomplete as per `ToBoolean` (7.1.2).
+features: [Symbol.iterator]
 ---*/
 
 var iterable = {};

test/language/statements/for-of/iterator-next-result-type.js

@@ -5,6 +5,7 @@ es6id: 13.6.4.13 S5.c
 description: >
     If Type(result) is not Object, throw a TypeError exception as per
     `IteratorNext` (7.4.2 S4)
+features: [Symbol.iterator]
 ---*/
 
 var iterable = {};

test/language/statements/for-of/iterator-next-result-value-attr.js

@@ -5,6 +5,7 @@ es6id: 13.6.4.13 S5.f
 description: >
     The `value` of iteration result objects should be retrieved using the Get
     abstract operation.
+features: [Symbol.iterator]
 ---*/
 
 var iterable = {};