Remove flags for ES2015 features shipped in M48

src/builtins.cc

 // Copyright 2012 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/builtins.h"
 
 #include "src/api.h"
 #include "src/api-natives.h"
 #include "src/arguments.h"
 #include "src/base/once.h"
@@ skipping 1243 matching lines @@
       UNREACHABLE();
       break;
   }
   visitor->increase_index_offset(length);
   return true;
 }
 
 
 bool HasConcatSpreadableModifier(Isolate* isolate, Handle<JSArray> obj) {
   DCHECK(isolate->IsFastArrayConstructorPrototypeChainIntact());
-  if (!FLAG_harmony_concat_spreadable) return false;
   Handle<Symbol> key(isolate->factory()->is_concat_spreadable_symbol());
   Maybe<bool> maybe = JSReceiver::HasProperty(obj, key);
   return maybe.FromMaybe(false);
 }
 
 
 static Maybe<bool> IsConcatSpreadable(Isolate* isolate, Handle<Object> obj) {
   HandleScope handle_scope(isolate);
   if (!obj->IsJSReceiver()) return Just(false);
-  if (FLAG_harmony_concat_spreadable) {
-    Handle<Symbol> key(isolate->factory()->is_concat_spreadable_symbol());
-    Handle<Object> value;
-    MaybeHandle<Object> maybeValue =
-        i::Runtime::GetObjectProperty(isolate, obj, key);
-    if (!maybeValue.ToHandle(&value)) return Nothing<bool>();
-    if (!value->IsUndefined()) return Just(value->BooleanValue());
-  }
+  Handle<Symbol> key(isolate->factory()->is_concat_spreadable_symbol());
+  Handle<Object> value;
+  MaybeHandle<Object> maybeValue =
+      i::Runtime::GetObjectProperty(isolate, obj, key);
+  if (!maybeValue.ToHandle(&value)) return Nothing<bool>();
+  if (!value->IsUndefined()) return Just(value->BooleanValue());
   return Object::IsArray(obj);
 }
 
 
 Object* Slow_ArrayConcat(Arguments* args, Handle<Object> species,
                          Isolate* isolate) {
   int argument_count = args->length();
 
   bool is_array_species = *species == isolate->context()->array_function();
 
@@ skipping 2910 matching lines @@
 BUILTIN_LIST_C(DEFINE_BUILTIN_ACCESSOR_C)
 BUILTIN_LIST_A(DEFINE_BUILTIN_ACCESSOR_A)
 BUILTIN_LIST_H(DEFINE_BUILTIN_ACCESSOR_H)
 BUILTIN_LIST_DEBUG_A(DEFINE_BUILTIN_ACCESSOR_A)
 #undef DEFINE_BUILTIN_ACCESSOR_C
 #undef DEFINE_BUILTIN_ACCESSOR_A
 
 
 }  // namespace internal
 }  // namespace v8