Fix the spec generator to use test rather than unittest

pkg/analysis_server/tool/spec/codegen_inttest_methods.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.
 
 /**
  * Code generation for the file "integration_test_methods.dart".
  */
 library codegenInttestMethods;
 
 import 'dart:convert';
@@ skipping 86 matching lines @@
     writeln('/**');
     writeln(' * Convenience methods for running integration tests');
     writeln(' */');
     writeln('library test.integration.methods;');
     writeln();
     writeln("import 'dart:async';");
     writeln();
     writeln("import 'package:analysis_server/plugin/protocol/protocol.dart';");
     writeln(
         "import 'package:analysis_server/src/protocol/protocol_internal.dart';");
-    writeln("import 'package:unittest/unittest.dart';");
+    writeln("import 'package:test/test.dart';");
     writeln();
     writeln("import 'integration_tests.dart';");
     writeln("import 'protocol_matchers.dart';");
     writeln();
     writeln();
     writeln('/**');
     writeln(' * Convenience methods for running integration tests');
     writeln(' */');
     writeln('abstract class IntegrationTestMixin {');
     indent(() {
@@ skipping 137 matching lines @@
         writeln('ResponseDecoder decoder = new ResponseDecoder($kind);');
         writeln("return new $resultClass.fromJson(decoder, 'result', result);");
       } else {
         writeln('expect(result, isNull);');
         writeln('return null;');
       }
     });
     writeln('}');
   }
 }