Add support for generic function type syntax, part 1

pkg/analysis_server/lib/src/services/refactoring/extract_method.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.refactoring.extract_method;
 
 import 'dart:async';
 
 import 'package:analysis_server/src/protocol_server.dart' hide Element;
 import 'package:analysis_server/src/services/correction/name_suggestion.dart';
@@ skipping 841 matching lines @@
     if (identical(node.variables, firstSelectedNode)) {
       invalidSelection(
           "Cannot extract initialization part of a 'for' statement.");
     } else if (node.updaters.contains(lastSelectedNode)) {
       invalidSelection("Cannot extract increment part of a 'for' statement.");
     }
     return null;
   }
 
   @override
+  Object visitGenericFunctionType(GenericFunctionType node) {
+    super.visitGenericFunctionType(node);
+    if (_isFirstSelectedNode(node)) {
+      invalidSelection('Cannot extract a single type reference.');
+    }
+    return null;
+  }
+
+  @override
   Object visitSimpleIdentifier(SimpleIdentifier node) {
     super.visitSimpleIdentifier(node);
     if (_isFirstSelectedNode(node)) {
       // name of declaration
       if (node.inDeclarationContext()) {
         invalidSelection('Cannot extract the name part of a declaration.');
       }
       // method name
       Element element = node.bestElement;
       if (element is FunctionElement || element is MethodElement) {
@@ skipping 372 matching lines @@
       return false;
     }
     for (int i = 0; i < parameterTypes.length; i++) {
       if (other.parameterTypes[i] != parameterTypes[i]) {
         return false;
       }
     }
     return true;
   }
 }