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

src/heap/objects-visiting.cc

 // Copyright 2011 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/heap/objects-visiting.h"
 
 #include "src/heap/mark-compact-inl.h"
 #include "src/heap/objects-visiting-inl.h"
 
 namespace v8 {
@@ skipping 264 matching lines @@
 };
 
 
 template <>
 struct WeakListVisitor<Context> {
   static void SetWeakNext(Context* context, Object* next) {
     context->set(Context::NEXT_CONTEXT_LINK, next, UPDATE_WEAK_WRITE_BARRIER);
   }
 
   static Object* WeakNext(Context* context) {
-    return context->get(Context::NEXT_CONTEXT_LINK);
+    return context->next_context_link();
   }
 
   static int WeakNextOffset() {
     return FixedArray::SizeFor(Context::NEXT_CONTEXT_LINK);
   }
 
   static void VisitLiveObject(Heap* heap, Context* context,
                               WeakObjectRetainer* retainer) {
     // Process the three weak lists linked off the context.
     DoWeakList<JSFunction>(heap, context, retainer,
@@ skipping 57 matching lines @@
 };
 
 
 template Object* VisitWeakList<Context>(Heap* heap, Object* list,
                                         WeakObjectRetainer* retainer);
 
 template Object* VisitWeakList<AllocationSite>(Heap* heap, Object* list,
                                                WeakObjectRetainer* retainer);
 }  // namespace internal
 }  // namespace v8