Return MaybeHandle from Invoke.

src/handles.h

Index: src/handles.h
diff --git a/src/handles.h b/src/handles.h
index 1100f5b836bf5b6c27953561a7b239a12668b31a..b27394ac97e009932904793265586f88b165ee98 100644
--- a/src/handles.h
+++ b/src/handles.h
@@ -319,9 +319,7 @@ enum KeyCollectionType { LOCAL_ONLY, INCLUDE_PROTOS };
 // Computes the enumerable keys for a JSObject. Used for implementing
 // "for (n in object) { }".
 MUST_USE_RESULT MaybeHandle<FixedArray> GetKeysInFixedArrayFor(
-    Handle<JSReceiver> object,
-    KeyCollectionType type);
-MUST_USE_RESULT MaybeHandle<JSArray> GetKeysFor(Handle<JSReceiver> object);
+    Handle<JSReceiver> object, KeyCollectionType type);
 Handle<FixedArray> ReduceFixedArrayTo(Handle<FixedArray> array, int length);
 Handle<FixedArray> GetEnumPropertyKeys(Handle<JSObject> object,
                                        bool cache_result);