cleanup duplicate fasta scanner methods

pkg/front_end/lib/src/fasta/scanner/abstract_scanner.dart

 // Copyright (c) 2012, 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 fasta.scanner.abstract_scanner;
 
 import 'dart:collection' show ListMixin;
 
 import 'dart:typed_data' show Uint16List, Uint32List;
 
@@ skipping 116 matching lines @@
    * Returns the current string offset.
    *
    * In the [StringScanner] this is identical to the [scanOffset]. In the
    * [Utf8BytesScanner] it is computed based on encountered UTF-8 characters.
    */
   int get stringOffset;
 
   /**
    * Returns the first token scanned by this [Scanner].
    */
-  Token firstToken();
+  Token firstToken() => tokens.next;
 
   /**
    * Returns the last token scanned by this [Scanner].
    */
-  Token previousToken();
+  Token previousToken() => tail;

[ahe, 2017/03/14 14:09:27]

I think we can delete this method.

[danrubel, 2017/03/14 16:55:15]

Done.

 
   /**
    * Notifies that a new token starts at current offset.
    */
   void beginToken() {
     tokenStart = stringOffset;
   }
 
   /**
    * Appends a substring from the scan offset [:start:] to the current
@@ skipping 1088 matching lines @@
       switchToUint32(newLength);
     }
   }
 
   void switchToUint32(int newLength) {
     final newArray = new Uint32List(newLength);
     newArray.setRange(0, arrayLength, array);
     array = newArray;
   }
 }