[FeedbackVector] Clarify the way the feedback vector is installed.

src/compiler.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/compiler.h"
 
 #include <algorithm>
 #include <memory>
 
 #include "src/asmjs/asm-js.h"
@@ skipping 1437 matching lines @@
   // If caller is strict mode, the result must be in strict mode as well.
   DCHECK(is_sloppy(language_mode) || is_strict(shared_info->language_mode()));
 
   Handle<JSFunction> result;
   if (eval_result.has_shared()) {
     if (eval_result.has_vector()) {
       result = isolate->factory()->NewFunctionFromSharedFunctionInfo(
           shared_info, context, vector, NOT_TENURED);
     } else {
       result = isolate->factory()->NewFunctionFromSharedFunctionInfo(
-          shared_info, context, isolate->factory()->undefined_cell(),
-          NOT_TENURED);
+          shared_info, context, NOT_TENURED);
       JSFunction::EnsureLiterals(result);
       // Make sure to cache this result.
       Handle<Cell> new_vector(result->feedback_vector_cell(), isolate);
       compilation_cache->PutEval(source, outer_info, context, shared_info,
                                  new_vector, eval_scope_position);
     }
   } else {
     result = isolate->factory()->NewFunctionFromSharedFunctionInfo(
         shared_info, context, NOT_TENURED);
     JSFunction::EnsureLiterals(result);
@@ skipping 359 matching lines @@
   }
 
   if (shared->is_compiled()) {
     // TODO(mvstanton): pass pretenure flag to EnsureLiterals.
     JSFunction::EnsureLiterals(function);
   }
 }
 
 }  // namespace internal
 }  // namespace v8