Start unraveling circularities between analyzer and front_end/kernel.

pkg/front_end/test/scanner_roundtrip_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/analyzer/token_utils.dart';
+import 'package:analyzer/src/fasta/token_utils.dart';
 import 'package:front_end/src/fasta/scanner/precedence.dart';
 import 'package:front_end/src/scanner/token.dart';
 import 'package:front_end/src/fasta/scanner/string_scanner.dart';
 import 'package:test/test.dart';
 import 'package:test_reflective_loader/test_reflective_loader.dart';
 
 import 'scanner_fasta_test.dart';
 import 'scanner_test.dart';
 
 main() {
@@ skipping 241 matching lines @@
 
     for (PrecedenceInfo info in PrecedenceInfo.all) {
       assertIsOperator(info.value, operatorLexemes.contains(info.value));
     }
 
     for (TokenType tt in new List.from(allTokenTypes)) {
       assertIsOperator(tt.lexeme, operatorTokenTypes.contains(tt));
     }
   }
 }