Create a public API for contributing fixes and make fixes pluggable

pkg/analysis_server/test/edit/fixes_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.fixes;
 
 import 'dart:async';
 
 import 'package:analysis_server/src/edit/edit_domain.dart';
+import 'package:analysis_server/src/plugin/server_plugin.dart';
 import 'package:analysis_server/src/protocol.dart';
+import 'package:analyzer/src/plugin/plugin_impl.dart';
 import 'package:unittest/unittest.dart' hide ERROR;
 
 import '../analysis_abstract.dart';
 import '../reflective_tests.dart';
 
 main() {
   groupSep = ' | ';
   runReflectiveTests(FixesTest);
 }
 
 @reflectiveTest
 class FixesTest extends AbstractAnalysisTest {
   @override
   void setUp() {
     super.setUp();
     createProject();
-    handler = new EditDomainHandler(server);
+    ExtensionManager manager = new ExtensionManager();
+    ServerPlugin plugin = new ServerPlugin();
+    manager.processPlugins([plugin]);
+    handler = new EditDomainHandler(server, plugin);
   }
 
   Future test_fixUndefinedClass() {
     addTestFile('''
 main() {
   Future<String> x = null;
 }
 ''');
     return waitForTasksFinished().then((_) {
       List<AnalysisErrorFixes> errorFixes = _getFixesAt('Future<String>');
@@ skipping 46 matching lines @@
     return _getFixes(offset);
   }
 
   void _isSyntacticErrorWithSingleFix(AnalysisErrorFixes fixes) {
     AnalysisError error = fixes.error;
     expect(error.severity, AnalysisErrorSeverity.ERROR);
     expect(error.type, AnalysisErrorType.SYNTACTIC_ERROR);
     expect(fixes.fixes, hasLength(1));
   }
 }