[es6] Partially implement Reflect.setPrototypeOf.

src/api.cc

Index: src/api.cc
diff --git a/src/api.cc b/src/api.cc
index d3c1cfb23f32fdee4672a9b97fe82cf748f262c2..b32ae51c4dc24fabcc64a4da2d60e95fa12fc94e 100644
--- a/src/api.cc
+++ b/src/api.cc
@@ -3685,8 +3685,9 @@ Maybe<bool> v8::Object::SetPrototype(Local<Context> context,
   // We do not allow exceptions thrown while setting the prototype
   // to propagate outside.
   TryCatch try_catch(reinterpret_cast<v8::Isolate*>(isolate));
-  auto result = i::JSObject::SetPrototype(self, value_obj, false);
-  has_pending_exception = result.is_null();
+  auto result =
+      i::JSObject::SetPrototype(self, value_obj, false, i::THROW_ON_ERROR);
+  has_pending_exception = result.IsNothing();
   RETURN_ON_FAILED_EXECUTION_PRIMITIVE(bool);
   return Just(true);
 }