Revert "cleanup unused incremental resolution"

pkg/front_end/test/token_test.dart

Index: pkg/front_end/test/token_test.dart
diff --git a/pkg/front_end/test/token_test.dart b/pkg/front_end/test/token_test.dart
index bf005dca2a78fc686a5551939b14720081b8b616..5d014fef96de2de1a325b50f1dc81a0ac54fbbf2 100644
--- a/pkg/front_end/test/token_test.dart
+++ b/pkg/front_end/test/token_test.dart
@@ -19,6 +19,16 @@ main() {
 /// 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