Count closures using the feedback vector cell map, specialize if count==1.

src/objects.cc

 // Copyright 2015 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/objects.h"
 
 #include <cmath>
 #include <iomanip>
 #include <memory>
 #include <sstream>
@@ skipping 12100 matching lines @@
 void JSFunction::EnsureLiterals(Handle<JSFunction> function) {
   Handle<SharedFunctionInfo> shared(function->shared());
   Isolate* isolate = shared->GetIsolate();
 
   FeedbackVectorState state = function->GetFeedbackVectorState(isolate);
   switch (state) {
     case TOP_LEVEL_SCRIPT_NEEDS_VECTOR: {
       // A top level script didn't get it's literals installed.
       Handle<FeedbackVector> feedback_vector =
           FeedbackVector::New(isolate, shared);
-      Handle<Cell> new_cell = isolate->factory()->NewCell(feedback_vector);
+      Handle<Cell> new_cell =
+          isolate->factory()->NewOneClosureCell(feedback_vector);
       function->set_feedback_vector_cell(*new_cell);
       break;
     }
     case NEEDS_VECTOR: {
       Handle<FeedbackVector> feedback_vector =
           FeedbackVector::New(isolate, shared);
       function->feedback_vector_cell()->set_value(*feedback_vector);
       break;
     }
     case HAS_VECTOR:
@@ skipping 8061 matching lines @@
       // depend on this.
       return DICTIONARY_ELEMENTS;
     }
     DCHECK_LE(kind, LAST_ELEMENTS_KIND);
     return kind;
   }
 }
 
 }  // namespace internal
 }  // namespace v8