[runtime][ic] Constant field tracking support.

src/json-parser.cc

Index: src/json-parser.cc
diff --git a/src/json-parser.cc b/src/json-parser.cc
index 7c0a83c5d9d7016b8afc93b10b7b41b444278b84..2ec79caefcd10009234ebfad082507a1157db7ac 100644
--- a/src/json-parser.cc
+++ b/src/json-parser.cc
@@ -399,8 +399,8 @@ Handle<Object> JsonParser<seq_one_byte>::ParseJsonObject() {
                    ->NowContains(value)) {
             Handle<FieldType> value_type(
                 value->OptimalType(isolate(), expected_representation));
-            Map::GeneralizeField(target, descriptor, expected_representation,
-                                 value_type);
+            Map::GeneralizeField(target, descriptor, details.constness(),
+                                 expected_representation, value_type);
           }
           DCHECK(target->instance_descriptors()
                      ->GetFieldType(descriptor)