Fix another false positive for not used function type alias.

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:math" as math;
 import 'dart:collection';
 
 import 'package:analyzer/src/generated/utilities_collection.dart';
@@ skipping 4522 matching lines @@
       if (element == null ||
           element is! LocalElement && !identical(element, _enclosingExec)) {
         usedElements.members.add(node.name);
         if (isIdentifierRead) {
           usedElements.readMembers.add(node.name);
         }
       }
     }
   }
 
-  @override
-  visitTypeName(TypeName node) {
-    _useIdentifierElement(node.name);
-  }
-
   /**
    * Marks an [Element] of [node] as used in the library.
    */
   void _useIdentifierElement(Identifier node) {
     Element element = node.staticElement;
     if (element == null) {
       return;
     }
     // check if a local element
     if (!identical(element.library, _enclosingLibrary)) {
@@ skipping 10857 matching lines @@
     nonFields.add(node);
     return null;
   }
 
   @override
   Object visitNode(AstNode node) => node.accept(TypeResolverVisitor_this);
 
   @override
   Object visitWithClause(WithClause node) => null;
 }