Migrate UnlinkedParam.defaultValue to UnlinkedExecutable.bodyExpr.

pkg/analyzer/lib/src/dart/element/element.dart

 // Copyright (c) 2014, 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 analyzer.src.dart.element.element;
 
 import 'dart:collection';
 import 'dart:math' show min;
 
 import 'package:analyzer/dart/ast/ast.dart';
@@ skipping 1809 matching lines @@
   /**
    * Initialize using the given serialized information.
    */
   DefaultParameterElementImpl.forSerialized(
       UnlinkedParam unlinkedParam, ElementImpl enclosingElement)
       : super.forSerialized(unlinkedParam, enclosingElement);
 
   @override
   Expression get constantInitializer {
     if (_unlinkedParam != null) {
-      UnlinkedConst defaultValue = _unlinkedParam.defaultValue;
+      UnlinkedConst defaultValue = _unlinkedParam.initializer?.bodyExpr;
       if (defaultValue == null) {
         return null;
       }
       return super.constantInitializer ??= enclosingUnit.resynthesizerContext
           .buildExpression(this, defaultValue);
     }
     return super.constantInitializer;
   }
 
   @override
@@ skipping 3900 matching lines @@
 
   @override
   void set const3(bool isConst) {
     assert(_unlinkedParam == null);
     super.const3 = isConst;
   }
 
   @override
   String get defaultValueCode {
     if (_unlinkedParam != null) {
-      if (_unlinkedParam.defaultValue == null) {
+      if (_unlinkedParam.initializer?.bodyExpr == null) {
         return null;
       }
       return _unlinkedParam.defaultValueCode;
     }
     return _defaultValueCode;
   }
 
   /**
    * Set Dart code of the default value.
    */
@@ skipping 1160 matching lines @@
 
   @override
   void visitElement(Element element) {
     int offset = element.nameOffset;
     if (offset != -1) {
       map[offset] = element;
     }
     super.visitElement(element);
   }
 }