Fix constructors for HLoadNamedField.

src/hydrogen-check-elimination.cc

 // Copyright 2013 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 "hydrogen-check-elimination.h"
 #include "hydrogen-alias-analysis.h"
 #include "hydrogen-flow-engine.h"
 
 #define GLOBAL 1
 
@@ skipping 322 matching lines @@
     } else {
       // No entry; insert a new one.
       Insert(object, instr, instr->maps());
     }
   }
 
   void ReduceLoadNamedField(HLoadNamedField* instr) {
     // Reduce a load of the map field when it is known to be a constant.
     if (!instr->access().IsMap()) {
       // Check if we introduce field maps here.
-      if (instr->maps()->size() != 0) {
-        Insert(instr, instr, instr->maps());
+      MapSet maps = instr->maps();
+      if (maps != NULL) {
+        ASSERT_NE(0, maps->size());
+        Insert(instr, NULL, maps);
       }
       return;
     }
 
     HValue* object = instr->object()->ActualValue();
     MapSet maps = FindMaps(object);
     if (maps == NULL || maps->size() != 1) return;  // Not a constant.
 
     Unique<Map> map = maps->at(0);
     HConstant* constant = HConstant::CreateAndInsertBefore(
@@ skipping 301 matching lines @@
   PRINT_STAT(removed_cho);
   PRINT_STAT(narrowed);
   PRINT_STAT(loads);
   PRINT_STAT(empty);
   PRINT_STAT(compares_true);
   PRINT_STAT(compares_false);
   PRINT_STAT(transitions);
 }
 
 } }  // namespace v8::internal