Issue 22027. When parameters has function type alias type, use its name.

pkg/analysis_server/lib/src/services/correction/util.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 services.src.correction.util;
 
 import 'dart:math';
 
 import 'package:analysis_server/src/protocol.dart' show SourceChange,
     SourceEdit;
@@ skipping 859 matching lines @@
   /**
    * @return the source for the parameter with the given type and name.
    */
   String getParameterSource(DartType type, String name,
       Set<LibraryElement> librariesToImport) {
     // no type
     if (type == null || type.isDynamic) {
       return name;
     }
     // function type
-    if (type is FunctionType) {
+    if (type is FunctionType && type.element.isSynthetic) {
       FunctionType functionType = type;
       StringBuffer sb = new StringBuffer();
       // return type
       DartType returnType = functionType.returnType;
       if (returnType != null && !returnType.isDynamic) {
         String returnTypeSource = getTypeSource(returnType, librariesToImport);
         sb.write(returnTypeSource);
         sb.write(' ');
       }
       // parameter name
@@ skipping 577 matching lines @@
 
   @override
   Object visitExpression(Expression node) {
     if (node is BinaryExpression && node.operator.type == groupOperatorType) {
       return super.visitNode(node);
     }
     operands.add(node);
     return null;
   }
 }