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

src/lookup.h

Index: src/lookup.h
diff --git a/src/lookup.h b/src/lookup.h
index 4cd4ece75d68a3af1823f4101476cc3ead66395d..13286deea3977cfcf10cc90df0b1c11e374e0161 100644
--- a/src/lookup.h
+++ b/src/lookup.h
@@ -263,9 +263,10 @@ class LookupIterator final BASE_EMBEDDED {
   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();
     }
   }
@@ -353,8 +354,6 @@ class LookupIterator final BASE_EMBEDDED {
 
   State NotFound(JSReceiver* const holder) const;
 
-  bool HolderIsInContextIndex(uint32_t index) const;
-
   // If configuration_ becomes mutable, update
   // HolderIsReceiverOrHiddenPrototype.
   const Configuration configuration_;