Update ObjectToString to Harmony-draft algorithm

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 8a052ff5e64b34b86aa577fbc8106d093eca8b16..25bd0de79da54e98f4eaac2d7a734ac9ba6f1d46 100644
--- a/test/mjsunit/es6/generators-objects.js
+++ b/test/mjsunit/es6/generators-objects.js
@@ -25,7 +25,7 @@
 // (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
 // OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
 
-// Flags: --harmony-scoping --allow-natives-syntax
+// Flags: --harmony-scoping --allow-natives-syntax --harmony-tostring
 
 // Test instantations of generators.
 
@@ -66,6 +66,7 @@ function TestGeneratorObject() {
   assertTrue(iter instanceof g);
   assertEquals("Generator", %_ClassOf(iter));
   assertEquals("[object Generator]", String(iter));
+  assertEquals("[object Generator]", Object.prototype.toString.call(iter));
   assertEquals([], Object.getOwnPropertyNames(iter));
   assertTrue(iter !== new g());
 }