Update copyright notices in front_end package.

pkg/front_end/lib/src/scanner/reader.dart

-// Copyright (c) 2014, the Dart project authors.  Please see the AUTHORS file
+// Copyright (c) 2016, 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.
 
 /**
  * An object used by the scanner to read the characters to be scanned.
  */
 abstract class CharacterReader {
   /**
    * The current offset relative to the beginning of the source. Return the
    * initial offset if the scanner has not yet scanned the source code, and one
@@ skipping 23 matching lines @@
    * location to be excluded if the offset is negative.
    */
   String getString(int start, int endDelta);
 
   /**
    * Return the character at the current position without changing the current
    * position.
    */
   int peek();
 }