Make it possible to generate headers with the correct year

pkg/analyzer/lib/src/codegen/tools.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.
 
 /**
  * Tools for generating code in analyzer and analysis server.
  */
 library analyzer.src.codegen.tools;
 
 import 'dart:io';
@@ skipping 137 matching lines @@
     if (containsOnlyWhitespace(docs)) {
       return;
     }
     write(codeGeneratorSettings.lineCommentLineLeader);
     int width = codeGeneratorSettings.commentLineLength;
     indentBy(codeGeneratorSettings.lineCommentLineLeader, () {
       write(nodesToText(docs, width - _state.indent.length, false));
     });
   }
 
-  void outputHeader({bool javaStyle: false}) {
+  void outputHeader({bool javaStyle: false, String year = null}) {
     String header;
     if (codeGeneratorSettings.languageName == 'java') {
       header = '''
 /*
- * Copyright (c) 2015, the Dart project authors.
+ * Copyright (c) ${year ?? '2015'}, the Dart project authors.
  *
  * Licensed under the Eclipse Public License v1.0 (the "License"); you may not use this file except
  * in compliance with the License. You may obtain a copy of the License at
  *
  * http://www.eclipse.org/legal/epl-v10.html
  *
  * Unless required by applicable law or agreed to in writing, software distributed under the License
  * is distributed on an "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express
  * or implied. See the License for the specific language governing permissions and limitations under
  * the License.
  *
  * This file has been automatically generated.  Please do not edit it manually.
  * To regenerate the file, use the script "pkg/analysis_server/tool/spec/generate_files".
  */''';
     } else if (codeGeneratorSettings.languageName == 'python') {
       header = '''
-# Copyright (c) 2014, the Dart project authors.  Please see the AUTHORS file
+# Copyright (c) ${year ?? '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.
 #
 # This file has been automatically generated.  Please do not edit it manually.
 # To regenerate the file, use the script
 # "pkg/analysis_server/tool/spec/generate_files".
 ''';
     } else {
       header = '''
-// Copyright (c) 2014, the Dart project authors.  Please see the AUTHORS file
+// Copyright (c) ${year ?? '2014'}, the Dart project authors.  Please see the AUTHORS file
 // for details. All rights reserved. Use of this source code is governed by a
 // BSD-style license that can be found in the LICENSE file.
 //
 // This file has been automatically generated.  Please do not edit it manually.
 // To regenerate the file, use the script
 // "pkg/analysis_server/tool/spec/generate_files".
 ''';
     }
     writeln(header.trim());
   }
@@ skipping 399 matching lines @@
     if (lines.last.isEmpty) {
       lines.removeLast();
       buffer.add(new dom.Text(lines.join('\n$indent') + '\n'));
       indentNeeded = true;
     } else {
       buffer.add(new dom.Text(lines.join('\n$indent')));
       indentNeeded = false;
     }
   }
 }