[runtime] enable fast key accumulator by default

src/keys.cc

 // Copyright 2013 the V8 project authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #include "src/keys.h"
 
 #include "src/api-arguments.h"
 #include "src/elements.h"
 #include "src/factory.h"
 #include "src/identity-map.h"
@@ skipping 13 matching lines @@
 static bool ContainsOnlyValidKeys(Handle<FixedArray> array) {
   int len = array->length();
   for (int i = 0; i < len; i++) {
     Object* e = array->get(i);
     if (!(e->IsName() || e->IsNumber())) return false;
   }
   return true;
 }
 
 }  // namespace
+
+// static
 MaybeHandle<FixedArray> KeyAccumulator::GetKeys(
     Handle<JSReceiver> object, KeyCollectionMode mode, PropertyFilter filter,
     GetKeysConversion keys_conversion, bool filter_proxy_keys, bool is_for_in) {
   Isolate* isolate = object->GetIsolate();
-  KeyAccumulator accumulator(isolate, mode, filter);
+  FastKeyAccumulator accumulator(isolate, object, mode, filter);
   accumulator.set_filter_proxy_keys(filter_proxy_keys);
   accumulator.set_is_for_in(is_for_in);
-  MAYBE_RETURN(accumulator.CollectKeys(object, object),
-               MaybeHandle<FixedArray>());
   return accumulator.GetKeys(keys_conversion);
 }
 
 Handle<FixedArray> KeyAccumulator::GetKeys(GetKeysConversion convert) {
   if (keys_.is_null()) {
     return isolate_->factory()->empty_fixed_array();
   }
   if (mode_ == KeyCollectionMode::kOwnOnly &&
       keys_->map() == isolate_->heap()->fixed_array_map()) {
     return Handle<FixedArray>::cast(keys_);
@@ skipping 807 matching lines @@
       Nothing<bool>());
   bool prev_filter_proxy_keys_ = filter_proxy_keys_;
   filter_proxy_keys_ = false;
   Maybe<bool> result = AddKeysFromJSProxy(proxy, keys);
   filter_proxy_keys_ = prev_filter_proxy_keys_;
   return result;
 }
 
 }  // namespace internal
 }  // namespace v8