Merge two constants.dart into one.

pkg/analysis_server/test/analysis_hover_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.domain.analysis.hover;
 
 import 'dart:async';
 
 import 'package:analysis_server/src/computer/computer_hover.dart';
 import 'package:analysis_server/src/constants.dart';
 import 'package:analysis_server/src/protocol.dart';
-import 'package:analysis_server/src/services/constants.dart';
 import 'package:analysis_testing/reflective_tests.dart';
 import 'package:unittest/unittest.dart';
 
 import 'analysis_abstract.dart';
 
 
 main() {
   groupSep = ' | ';
   runReflectiveTests(AnalysisHoverTest);
 }
@@ skipping 200 matching lines @@
 library my.library;
 main() {
   // nothing
 }
 ''');
     return prepareHover('nothing').then((Hover hover) {
       expect(hover, isNull);
     });
   }
 }