Introduce FieldIndex to unify and abstract property/field offset

src/utils.h

 // 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.
 
 #ifndef V8_UTILS_H_
 #define V8_UTILS_H_
 
 #include <limits.h>
 #include <stdlib.h>
 #include <string.h>
@@ skipping 230 matching lines @@
 template<class T, int shift, int size, class U>
 class BitFieldBase {
  public:
   // A type U mask of bit field.  To use all bits of a type U of x bits
   // in a bitfield without compiler warnings we have to compute 2^x
   // without using a shift count of x in the computation.
   static const U kOne = static_cast<U>(1U);
   static const U kMask = ((kOne << shift) << size) - (kOne << shift);
   static const U kShift = shift;
   static const U kSize = size;
+  static const U kNext = kShift + kSize;
 
   // Value for the field with all bits set.
   static const T kMax = static_cast<T>((1U << size) - 1);
 
   // Tells whether the provided value fits into the bit field.
   static bool is_valid(T value) {
     return (static_cast<U>(value) & ~static_cast<U>(kMax)) == 0;
   }
 
   // Returns a type U with the bit field value encoded.
@@ skipping 1287 matching lines @@
   // Add formatted contents like printf based on a va_list.
   void AddFormattedList(const char* format, va_list list);
  private:
   DISALLOW_IMPLICIT_CONSTRUCTORS(StringBuilder);
 };
 
 
 } }  // namespace v8::internal
 
 #endif  // V8_UTILS_H_