Revert "cleanup unused incremental resolution"

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

 // Copyright (c) 2011, 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.token;
 
 import '../../scanner/token.dart' as analyzer;
 import '../../scanner/token.dart' show TokenType;
 
 import 'token_constants.dart' show IDENTIFIER_TOKEN;
@@ skipping 59 matching lines @@
     charOffset = newOffset;
   }
 
   @override
   int get length => charCount;
 
   @override
   int get end => charEnd;
 
   @override
+  void applyDelta(int delta) {
+    charOffset += delta;
+    CommentToken token = precedingComments;
+    while (token != null) {
+      token.applyDelta(delta);
+      token = token.next;
+    }
+  }
+
+  @override
   analyzer.Token copy() {
     return copyWithoutComments()
       ..precedingComments = copyComments(precedingComments);
   }
 
   @override
   analyzer.Token copyComments(analyzer.Token token) {
     if (token == null) {
       return null;
     }
@@ skipping 476 matching lines @@
       identical(value, "<=") ||
       identical(value, "<") ||
       identical(value, "&") ||
       identical(value, "^") ||
       identical(value, "|");
 }
 
 bool isTernaryOperator(String value) => identical(value, "[]=");
 
 bool isMinusOperator(String value) => identical(value, "-");