[proxies] use [[GetPrototypeOf]] trap in for-in

src/objects.cc

Index: src/objects.cc
diff --git a/src/objects.cc b/src/objects.cc
index 79dda37866f3e452ed6d1a33862e8375d5fe68b5..fd2a2c6ecf5fad06ae458acb5e92aeb4630c1863 100644
--- a/src/objects.cc
+++ b/src/objects.cc
@@ -8659,7 +8659,7 @@ static Maybe<bool> GetKeys_Internal(Isolate* isolate,
                                           : PrototypeIterator::END_AT_NULL;
   for (PrototypeIterator iter(isolate, object,
                               PrototypeIterator::START_AT_RECEIVER, end);
-       !iter.IsAtEnd(); iter.Advance()) {
+       !iter.IsAtEnd();) {
     Handle<JSReceiver> current =
         PrototypeIterator::GetCurrent<JSReceiver>(iter);
     Maybe<bool> result = Just(false);  // Dummy initialization.
@@ -8675,6 +8675,9 @@ static Maybe<bool> GetKeys_Internal(Isolate* isolate,
     }
     MAYBE_RETURN(result, Nothing<bool>());
     if (!result.FromJust()) break;  // |false| means "stop iterating".
+    if (!iter.AdvanceFollowingProxies(PrototypeIterator::STOP_EARLY)) {
+      return Nothing<bool>();
+    }
   }
   return Just(true);
 }