Don't resynthesize field types during class members resynthesis.

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

 // Copyright (c) 2016, 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 serialization.summarize_ast;
 
 import 'package:analyzer/dart/ast/ast.dart';
 import 'package:analyzer/dart/ast/token.dart';
 import 'package:analyzer/dart/ast/visitor.dart';
 import 'package:analyzer/dart/element/type.dart' show DartType;
@@ skipping 692 matching lines @@
    * values are the indices of those local functions relative to their siblings.
    */
   Map<int, int> serializeFunctionBody(
       UnlinkedExecutableBuilder b,
       List<ConstructorInitializer> initializers,
       AstNode body,
       bool serializeBodyExpr,
       bool serializeBody) {
     if (body is BlockFunctionBody || body is ExpressionFunctionBody) {
       for (UnlinkedParamBuilder parameter in b.parameters) {
-        parameter.visibleOffset = body.offset;
-        parameter.visibleLength = body.length;
+        if (!parameter.isInitializingFormal) {
+          parameter.visibleOffset = body.offset;
+          parameter.visibleLength = body.length;
+        }
       }
     }
     List<UnlinkedExecutableBuilder> oldExecutables = executables;
     List<UnlinkedLabelBuilder> oldLabels = labels;
     List<UnlinkedVariableBuilder> oldVariables = variables;
     Map<int, int> oldLocalClosureIndexMap = _localClosureIndexMap;
     bool oldSerializeClosureBodyExprs = _serializeClosureBodyExprs;
     executables = <UnlinkedExecutableBuilder>[];
     labels = <UnlinkedLabelBuilder>[];
     variables = <UnlinkedVariableBuilder>[];
@@ skipping 690 matching lines @@
 /**
  * A [_TypeParameterScope] is a [_Scope] which defines [_ScopedTypeParameter]s.
  */
 class _TypeParameterScope extends _Scope {
   /**
    * Get the number of [_ScopedTypeParameter]s defined in this
    * [_TypeParameterScope].
    */
   int get length => _definedNames.length;
 }