Clean up package imports and library names

pkg/analyzer/test/src/util/yaml_test.dart

 // Copyright (c) 2015, 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 analyzer.test.util.yaml;
+library analyzer.src.test.util.yaml_test;
 
 import 'package:analyzer/src/util/yaml.dart';
 import 'package:unittest/unittest.dart';
 
 import '../../utils.dart';
 
 main() {
   initializeTestEnvironment();
 
   group('yaml', () {
@@ skipping 79 matching lines @@
         expect(merge(1, 'foo'), 'foo');
         expect(merge({'foo': 1}, 'foo'), 'foo');
       });
     });
   });
 }
 
 final Merger merger = new Merger();
 
 Object merge(Object o1, Object o2) => merger.merge(o1, o2);