Remove unnecessary code from the json-parser.

src/json-parser.h

 // Copyright 2011 the V8 project authors. All rights reserved.
 // Redistribution and use in source and binary forms, with or without
 // modification, are permitted provided that the following conditions are
 // met:
 //
 //     * Redistributions of source code must retain the above copyright
 //       notice, this list of conditions and the following disclaimer.
 //     * Redistributions in binary form must reproduce the above
 //       copyright notice, this list of conditions and the following
 //       disclaimer in the documentation and/or other materials provided
@@ skipping 439 matching lines @@
     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];
-        // If the target representation is double and the value is already
-        // double, use the existing box.
-        if (FLAG_track_double_fields && value->IsSmi()) {
-          Representation representation =
-              map->instance_descriptors()->GetDetails(i).representation();
-          if (representation.IsDouble()) {
-            value = factory()->NewHeapNumber(
-                Handle<Smi>::cast(value)->value());
-          }
-        }
         json_object->FastPropertyAtPut(i, *value);
       }
     }
   }
   AdvanceSkipWhitespace();
   return scope.CloseAndEscape(json_object);
 }
 
 // Parse a JSON array. Position must be right at '['.
 template <bool seq_ascii>
@@ skipping 331 matching lines @@
 
   ASSERT_EQ('"', c0_);
   // Advance past the last '"'.
   AdvanceSkipWhitespace();
   return result;
 }
 
 } }  // namespace v8::internal
 
 #endif  // V8_JSON_PARSER_H_