[runtime] Add MapUpdater class that manages all kinds of map updates.

src/json-parser.cc

 // Copyright 2016 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 "src/json-parser.h"
 
 #include "src/char-predicates-inl.h"
 #include "src/conversions.h"
 #include "src/debug/debug.h"
 #include "src/factory.h"
@@ skipping 381 matching lines @@
             target->instance_descriptors()->GetDetails(descriptor);
         Representation expected_representation = details.representation();
 
         if (value->FitsRepresentation(expected_representation)) {
           if (expected_representation.IsHeapObject() &&
               !target->instance_descriptors()
                    ->GetFieldType(descriptor)
                    ->NowContains(value)) {
             Handle<FieldType> value_type(
                 value->OptimalType(isolate(), expected_representation));
-            Map::GeneralizeFieldType(target, descriptor,
-                                     expected_representation, value_type);
+            Map::GeneralizeField(target, descriptor, expected_representation,
+                                 value_type);
           }
           DCHECK(target->instance_descriptors()
                      ->GetFieldType(descriptor)
                      ->NowContains(value));
           properties.Add(value, zone());
           map = target;
           descriptor++;
           continue;
         } else {
           transitioning = false;
@@ skipping 389 matching lines @@
   AdvanceSkipWhitespace();
   return result;
 }
 
 // Explicit instantiation.
 template class JsonParser<true>;
 template class JsonParser<false>;
 
 }  // namespace internal
 }  // namespace v8