Introduce convenience methods into generated analysis server classes.

pkg/analysis_server/test/edit/assists_test.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 test.edit.assists;
 
 import 'dart:async';
 
 import 'package:analysis_server/src/edit/edit_domain.dart';
 import 'package:analysis_server/src/protocol.dart';
@@ skipping 97 matching lines @@
   }
 }
 ''');
     });
   }
 
   void _assertHasChange(String message, String expectedCode) {
     for (Change change in changes) {
       if (change.message == message) {
         String resultCode =
-            applySequence(testCode, change.fileEdits[0].edits);
+            SourceEdit.applySequence(testCode, change.fileEdits[0].edits);
         expect(resultCode, expectedCode);
         return;
       }
     }
     fail("Expected to find |$message| in\n" + changes.join('\n'));
   }
 }