Expose %IteratorPrototype% as an intrinsic in the public API.

test/cctest/test-api.cc

Index: test/cctest/test-api.cc
diff --git a/test/cctest/test-api.cc b/test/cctest/test-api.cc
index 251177cb4d9ce8366413f1108f5acf937ba93f2f..cf583382cefe3d0a104545d372cc5db161aee89c 100644
--- a/test/cctest/test-api.cc
+++ b/test/cctest/test-api.cc
@@ -25892,6 +25892,78 @@ TEST(AccessCheckedToStringTag) {
   CHECK_EQ(0, strcmp(*result_denied, "[object Object]"));
 }
 
+TEST(TemplateIteratorPrototypeIntrinsics) {
+  v8::Isolate* isolate = CcTest::isolate();
+  v8::HandleScope scope(isolate);
+  LocalContext env;
+
+  // Object templates.
+  {
+    Local<ObjectTemplate> object_template = v8::ObjectTemplate::New(isolate);
+    object_template->SetIntrinsicDataProperty(v8_str("iter_proto"),
+                                              v8::kIteratorPrototype);
+    Local<Object> object =
+        object_template->NewInstance(env.local()).ToLocalChecked();
+    CHECK(env->Global()->Set(env.local(), v8_str("obj"), object).FromJust());
+    ExpectTrue("obj.iter_proto === [][Symbol.iterator]().__proto__.__proto__");
+  }
+  // Setting %IteratorProto% on the function object's prototype template.
+  {
+    Local<FunctionTemplate> func_template = v8::FunctionTemplate::New(isolate);
+    func_template->PrototypeTemplate()->SetIntrinsicDataProperty(
+        v8_str("iter_proto"), v8::kIteratorPrototype);
+    Local<Function> func1 =
+        func_template->GetFunction(env.local()).ToLocalChecked();
+    CHECK(env->Global()->Set(env.local(), v8_str("func1"), func1).FromJust());
+    Local<Function> func2 =
+        func_template->GetFunction(env.local()).ToLocalChecked();
+    CHECK(env->Global()->Set(env.local(), v8_str("func2"), func2).FromJust());
+    ExpectTrue(
+        "func1.prototype.iter_proto === "
+        "[][Symbol.iterator]().__proto__.__proto__");
+    ExpectTrue(
+        "func2.prototype.iter_proto === "
+        "[][Symbol.iterator]().__proto__.__proto__");
+    ExpectTrue("func1.prototype.iter_proto === func2.prototype.iter_proto");
+
+    Local<Object> instance1 = func1->NewInstance(env.local()).ToLocalChecked();
+    CHECK(env->Global()
+              ->Set(env.local(), v8_str("instance1"), instance1)
+              .FromJust());
+    ExpectFalse("instance1.hasOwnProperty('iter_proto')");
+    ExpectTrue("'iter_proto' in instance1.__proto__");
+    ExpectTrue(
+        "instance1.iter_proto === [][Symbol.iterator]().__proto__.__proto__");
+  }
+  // Put %IteratorProto% in a function object's inheritance chain.
+  {
+    Local<FunctionTemplate> parent_template =
+        v8::FunctionTemplate::New(isolate);
+    parent_template->RemovePrototype();  // Remove so there is no name clash.

[caitp, 2017/03/29 12:36:44]

This will force the instantiated Function to be non-constructible, which I guess
is fine for most DOM interfaces, but still a bit strange.

I agree there doesn't appear to be much else you can do in the current API.

+    parent_template->SetIntrinsicDataProperty(v8_str("prototype"),
+                                              v8::kIteratorPrototype);
+    Local<FunctionTemplate> func_template = v8::FunctionTemplate::New(isolate);
+    func_template->Inherit(parent_template);
+
+    Local<Function> func =
+        func_template->GetFunction(env.local()).ToLocalChecked();
+    CHECK(env->Global()->Set(env.local(), v8_str("func"), func).FromJust());
+    ExpectTrue(
+        "func.prototype.__proto__ === "
+        "[][Symbol.iterator]().__proto__.__proto__");
+
+    Local<Object> func_instance =
+        func->NewInstance(env.local()).ToLocalChecked();
+    CHECK(env->Global()
+              ->Set(env.local(), v8_str("instance"), func_instance)
+              .FromJust());
+    ExpectTrue(
+        "instance.__proto__.__proto__ === "
+        "[][Symbol.iterator]().__proto__.__proto__");
+    ExpectTrue("instance.__proto__.__proto__.__proto__ === Object.prototype");
+  }
+}
+
 TEST(ObjectTemplateArrayProtoIntrinsics) {
   v8::Isolate* isolate = CcTest::isolate();
   v8::HandleScope scope(isolate);