Migrate UnlinkedParam.defaultValue to UnlinkedExecutable.bodyExpr.

pkg/analyzer/lib/src/summary/resynthesize.dart

 // Copyright (c) 2015, the Dart project authors.  Please see the AUTHORS file
 // for details. All rights reserved. Use of this source code is governed by a
 // BSD-style license that can be found in the LICENSE file.
 
 library summary_resynthesizer;
 
 import 'dart:collection';
 
 import 'package:analyzer/dart/ast/ast.dart';
 import 'package:analyzer/dart/ast/token.dart';
@@ skipping 2314 matching lines @@
     if (serializedParameter.isInitializingFormal) {
       FieldFormalParameterElementImpl initializingParameter;
       if (serializedParameter.kind == UnlinkedParamKind.required) {
         initializingParameter = new FieldFormalParameterElementImpl(
             serializedParameter.name, nameOffset);
       } else {
         DefaultFieldFormalParameterElementImpl defaultParameter =
             new DefaultFieldFormalParameterElementImpl(
                 serializedParameter.name, nameOffset);
         initializingParameter = defaultParameter;
-        if (serializedParameter.defaultValue != null) {
+        if (serializedParameter.initializer?.bodyExpr != null) {
           defaultParameter.constantInitializer = _buildConstExpression(
-              enclosingElement, serializedParameter.defaultValue);
+              enclosingElement, serializedParameter.initializer.bodyExpr);
           defaultParameter.defaultValueCode =
               serializedParameter.defaultValueCode;
         }
       }
       parameterElement = initializingParameter;
       initializingParameter.field = fields[serializedParameter.name];
     } else {
       if (serializedParameter.kind == UnlinkedParamKind.required) {
         parameterElement = new ParameterElementImpl.forSerialized(
             serializedParameter, enclosingElement);
@@ skipping 614 matching lines @@
   static String _getElementIdentifier(String name, ReferenceKind kind) {
     if (kind == ReferenceKind.topLevelPropertyAccessor ||
         kind == ReferenceKind.propertyAccessor) {
       if (!name.endsWith('=')) {
         return name + '?';
       }
     }
     return name;
   }
 }