Port and test more assists.

pkg/analysis_services/lib/correction/assist.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.correction.assist;
 
 import 'package:analysis_services/correction/change.dart';
 import 'package:analysis_services/search/search_engine.dart';
 import 'package:analysis_services/src/correction/assist.dart';
 import 'package:analyzer/src/generated/ast.dart';
 import 'package:analyzer/src/generated/source.dart';
 
 
 /**
- * Computes [Assist]s for the given location.
+ * Computes [Assist]s at the given location.
  *
  * Returns the computed [Assist]s, not `null`.
  */
 List<Assist> computeAssists(SearchEngine searchEngine, CompilationUnit unit,
     int offset, int length) {
   Source source = unit.element.source;
   String file = source.fullName;
   AssistProcessor processor =
       new AssistProcessor(searchEngine, source, file, unit, offset, length);
   return processor.compute();
@@ skipping 97 matching lines @@
           30,
           "Surround with 'try-finally'");
   static const SURROUND_WITH_WHILE =
       const AssistKind('SURROUND_WITH_WHILE', 30, "Surround with 'while'");
 
   final name;
   final int relevance;
   final String message;
 
   const AssistKind(this.name, this.relevance, this.message);
+
+  @override
+  String toString() => name;
 }