infer field formal parameter types

pkg/analyzer/lib/src/generated/resolver.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 engine.resolver;
 
 import 'dart:collection';
 
 import 'ast.dart';
 import 'constant.dart';
@@ skipping 13993 matching lines @@
   Object visitFieldFormalParameter(FieldFormalParameter node) {
     super.visitFieldFormalParameter(node);
     Element element = node.identifier.staticElement;
     if (element is ParameterElementImpl) {
       ParameterElementImpl parameter = element;
       FormalParameterList parameterList = node.parameters;
       if (parameterList == null) {
         DartType type;
         TypeName typeName = node.type;
         if (typeName == null) {
+          element.hasImplicitType = true;
           type = _dynamicType;
           if (parameter is FieldFormalParameterElement) {
             FieldElement fieldElement =
                 (parameter as FieldFormalParameterElement).field;
             if (fieldElement != null) {
               type = fieldElement.type;
             }
           }
         } else {
           type = _getType(typeName);
@@ skipping 1923 matching lines @@
     nonFields.add(node);
     return null;
   }
 
   @override
   Object visitNode(AstNode node) => node.accept(TypeResolverVisitor_this);
 
   @override
   Object visitWithClause(WithClause node) => null;
 }