Add %LoadMutableDouble index check.

src/field-index.h

 // Copyright 2014 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.
 
 #ifndef V8_FIELD_INDEX_H_
 #define V8_FIELD_INDEX_H_
 
 #include "src/property-details.h"
 #include "src/utils.h"
 
@@ skipping 12 matching lines @@
                                      int index,
                                      bool is_double = false);
   static FieldIndex ForInObjectOffset(int offset, Map* map = NULL);
   static FieldIndex ForDescriptor(Map* map, int descriptor_index);
   static FieldIndex ForLoadByFieldIndex(Map* map, int index);
   static FieldIndex ForKeyedLookupCacheIndex(Map* map, int index);
   static FieldIndex FromFieldAccessStubKey(int key);
 
   int GetLoadByFieldIndex() const;
 
+  static bool LoadByFieldIndexValid(int index);
+
   bool is_inobject() const {
     return IsInObjectBits::decode(bit_field_);
   }
 
   bool is_double() const {
     return IsDoubleBits::decode(bit_field_);
   }
 
   int offset() const {
     return index() * kPointerSize;
@@ skipping 62 matching lines @@
   class IsHiddenField
       : public BitField<bool, FirstInobjectPropertyOffsetBits::kNext, 1> {};
   STATIC_ASSERT(IsHiddenField::kNext <= 32);
 
   int bit_field_;
 };
 
 } }  // namespace v8::internal
 
 #endif