more work aligning fasta.Token with analyzer.Token

pkg/front_end/test/scanner_replacement_test.dart

 // Copyright (c) 2017, 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.
 
 import 'dart:convert' show UTF8;
 
 import 'package:front_end/src/fasta/scanner/recover.dart'
     show defaultRecoveryStrategy;
 import 'package:front_end/src/fasta/scanner.dart' as fasta;
 import 'package:front_end/src/fasta/scanner/token.dart' as fasta;
@@ skipping 301 matching lines @@
     var token = firstToken;
     // The default recovery strategy used by scanString
     // places all error tokens at the head of the stream.
     while (token.type == analyzer.TokenType.BAD_INPUT) {
       translateErrorToken(token,
           (ScannerErrorCode errorCode, int offset, List<Object> arguments) {
         listener.errors.add(new TestError(offset, errorCode, arguments));
       });
       token = token.next;
     }
-    if (!token.previousToken.isEof) {
+    if (!token.previous.isEof) {
       var head = new fasta.SymbolToken(analyzer.TokenType.EOF, -1);
       token.previous = head;
       head.next = token;
     }
     return token;
   }
 
   /// Assert that the tokens in the stream are correctly connected prev/next.
   void assertValidTokenStream(fasta.Token firstToken,
       {bool errorsFirst: false}) {
     fasta.Token token = firstToken;
-    fasta.Token previous = token.previousToken;
+    fasta.Token previous = token.previous;
     expect(previous.isEof, isTrue, reason: 'Missing leading EOF');
     expect(previous.next, token, reason: 'Invalid leading EOF');
     expect(previous.previous, previous, reason: 'Invalid leading EOF');
     if (errorsFirst) {
       while (!token.isEof && token is fasta.ErrorToken) {
         token = token.next;
       }
     }
     var isNotErrorToken = isNot(new isInstanceOf<fasta.ErrorToken>());
     while (!token.isEof) {
@@ skipping 24 matching lines @@
       } else if (token is fasta.UnmatchedToken) {
         expect(lastClosedGroup?.endGroup?.next, same(token),
             reason: 'Unexpected error token for group: $lastClosedGroup');
         expect(token.begin, lastClosedGroup);
       }
       token = token.next;
     }
     expect(openerStack, isEmpty, reason: 'Missing closers');
   }
 }