Introduce FieldIndex to unify and abstract property/field offset

src/json-parser.h

 // Copyright 2011 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_JSON_PARSER_H_
 #define V8_JSON_PARSER_H_
 
 #include "src/v8.h"
 
 #include "src/char-predicates-inl.h"
@@ skipping 396 matching lines @@
           } else {
             transitioning = false;
           }
         }
 
         // Commit the intermediate state to the object and stop transitioning.
         JSObject::AllocateStorageForMap(json_object, map);
         int length = properties.length();
         for (int i = 0; i < length; i++) {
           Handle<Object> value = properties[i];
-          json_object->FastPropertyAtPut(i, *value);
+          FieldIndex index = FieldIndex::ForPropertyIndex(*map, i);
+          json_object->FastPropertyAtPut(index, *value);
         }
       } else {
         key = ParseJsonInternalizedString();
         if (key.is_null() || c0_ != ':') return ReportUnexpectedCharacter();
 
         AdvanceSkipWhitespace();
         value = ParseJsonValue();
         if (value.is_null()) return ReportUnexpectedCharacter();
       }
 
       JSObject::SetOwnPropertyIgnoreAttributes(
           json_object, key, value, NONE).Assert();
     } while (MatchSkipWhiteSpace(','));
     if (c0_ != '}') {
       return ReportUnexpectedCharacter();
     }
 
     // If we transitioned until the very end, transition the map now.
     if (transitioning) {
       JSObject::AllocateStorageForMap(json_object, map);
       int length = properties.length();
       for (int i = 0; i < length; i++) {
         Handle<Object> value = properties[i];
-        json_object->FastPropertyAtPut(i, *value);
+        FieldIndex index = FieldIndex::ForPropertyIndex(*map, i);
+        json_object->FastPropertyAtPut(index, *value);
       }
     }
   }
   AdvanceSkipWhitespace();
   return scope.CloseAndEscape(json_object);
 }
 
 // Parse a JSON array. Position must be right at '['.
 template <bool seq_ascii>
 Handle<Object> JsonParser<seq_ascii>::ParseJsonArray() {
@@ skipping 329 matching lines @@
 
   ASSERT_EQ('"', c0_);
   // Advance past the last '"'.
   AdvanceSkipWhitespace();
   return result;
 }
 
 } }  // namespace v8::internal
 
 #endif  // V8_JSON_PARSER_H_