Set @@toStringTag on GeneratorFunction prototype.

test/mjsunit/es6/generators-objects.js

Index: test/mjsunit/es6/generators-objects.js
diff --git a/test/mjsunit/es6/generators-objects.js b/test/mjsunit/es6/generators-objects.js
index 25bd0de79da54e98f4eaac2d7a734ac9ba6f1d46..8039ca8bb14b8cc55d21f7d3d24aa8dbda248ae9 100644
--- a/test/mjsunit/es6/generators-objects.js
+++ b/test/mjsunit/es6/generators-objects.js
@@ -67,6 +67,8 @@ function TestGeneratorObject() {
   assertEquals("Generator", %_ClassOf(iter));
   assertEquals("[object Generator]", String(iter));
   assertEquals("[object Generator]", Object.prototype.toString.call(iter));
+  var gf = iter.__proto__.constructor;
+  assertEquals("[object GeneratorFunction]", Object.prototype.toString.call(gf));
   assertEquals([], Object.getOwnPropertyNames(iter));
   assertTrue(iter !== new g());

[caitp (gmail), 2014/11/27 15:05:11]

I think the reason I didn't add this before was that GeneratorFunction was not
exposed (it looks like the GeneratorFunction is meant to be exposed as a builtin
from the spec) --- would it make sense to have a TODO here for a simpler test
just involving `new GeneratorFunction`?

[Dmitry Lomov (no reviews), 2014/11/27 15:12:36]

GeneratorFucntion is not exposed per ES6 spec.

 }