Revert "cleanup unused incremental resolution"

pkg/front_end/test/token_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 'package:front_end/src/fasta/scanner/string_scanner.dart';
 import 'package:front_end/src/fasta/scanner/token.dart' as fasta;
 import 'package:front_end/src/scanner/token.dart';
 import 'package:front_end/src/scanner/reader.dart' as analyzer;
 import 'package:test/test.dart';
 import 'package:test_reflective_loader/test_reflective_loader.dart';
 import 'scanner_roundtrip_test.dart' show TestScanner;
 
 main() {
   defineReflectiveSuite(() {
     defineReflectiveTests(TokenTest);
   });
 }
 
 /// Assert that fasta PrecedenceInfo implements analyzer TokenType.
 @reflectiveTest
 class TokenTest {
+  void test_applyDelta() {
+    var scanner = new StringScanner('/* 1 */ foo', includeComments: true);
+    var token = scanner.tokenize();
+    expect(token.offset, 8);
+    expect(token.precedingComments.offset, 0);
+    token.applyDelta(12);
+    expect(token.offset, 20);
+    expect(token.precedingComments.offset, 12);
+  }
+
   void test_comments() {
     var source = '''
 /// Single line dartdoc comment
 class Foo {
   /**
    * Multi-line dartdoc comment
    */
   void bar() {
     // Single line comment
     int x = 0;
@@ skipping 169 matching lines @@
     // General tokens
     token = token.next;
     expect(token.lexeme, '&');
     expect(token.value(), '&');
     // String tokens
     token = token.next;
     expect(token.lexeme, '"home"');
     expect(token.value(), '"home"');
   }
 }