[runtime] Avoid @@isConcatSpreadable lookup for fast path Array.prototype.concat

src/lookup.h

 // Copyright 2014 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.
 
 #ifndef V8_LOOKUP_H_
 #define V8_LOOKUP_H_
 
 #include "src/factory.h"
 #include "src/isolate.h"
 #include "src/objects.h"
@@ skipping 245 matching lines @@
   inline Handle<InterceptorInfo> GetInterceptor() const {
     DCHECK_EQ(INTERCEPTOR, state_);
     InterceptorInfo* result =
         IsElement() ? GetInterceptor<true>(JSObject::cast(*holder_))
                     : GetInterceptor<false>(JSObject::cast(*holder_));
     return handle(result, isolate_);
   }
   Handle<Object> GetDataValue() const;
   void WriteDataValue(Handle<Object> value);
   inline void UpdateProtector() {
-    if (FLAG_harmony_species && !IsElement() &&
-        (*name_ == heap()->constructor_string() ||
-         *name_ == heap()->species_symbol())) {
+    if (IsElement()) return;
+    if (*name_ == heap()->is_concat_spreadable_symbol() ||
+        (FLAG_harmony_species && (*name_ == heap()->constructor_string() ||
+                                  *name_ == heap()->species_symbol()))) {
       InternalUpdateProtector();
     }
   }
 
  private:
   void InternalUpdateProtector();
 
   enum class InterceptorState {
     kUninitialized,
     kSkipNonMasking,
@@ skipping 67 matching lines @@
       Isolate* isolate, Handle<Object> receiver, uint32_t index = kMaxUInt32);
   inline static Handle<JSReceiver> GetRoot(Isolate* isolate,
                                            Handle<Object> receiver,
                                            uint32_t index = kMaxUInt32) {
     if (receiver->IsJSReceiver()) return Handle<JSReceiver>::cast(receiver);
     return GetRootForNonJSReceiver(isolate, receiver, index);
   }
 
   State NotFound(JSReceiver* const holder) const;
 
-  bool HolderIsInContextIndex(uint32_t index) const;
-
   // If configuration_ becomes mutable, update
   // HolderIsReceiverOrHiddenPrototype.
   const Configuration configuration_;
   State state_;
   bool has_property_;
   InterceptorState interceptor_state_;
   PropertyDetails property_details_;
   Isolate* const isolate_;
   Handle<Name> name_;
   Handle<Object> transition_;
   const Handle<Object> receiver_;
   Handle<JSReceiver> holder_;
   const Handle<JSReceiver> initial_holder_;
   const uint32_t index_;
   uint32_t number_;
 };
 
 
 }  // namespace internal
 }  // namespace v8
 
 #endif  // V8_LOOKUP_H_