remove fasta <--> analyzer token translation

pkg/front_end/test/scanner_fasta_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:analyzer/src/fasta/token_utils.dart';
 import 'package:front_end/src/fasta/scanner/error_token.dart' as fasta;
 import 'package:front_end/src/fasta/scanner/string_scanner.dart' as fasta;
 import 'package:front_end/src/fasta/scanner/token.dart' as fasta;
 import 'package:front_end/src/fasta/scanner/token_constants.dart' as fasta;
 import 'package:front_end/src/scanner/errors.dart';
 import 'package:front_end/src/scanner/token.dart';
 import 'package:test/test.dart';
 import 'package:test_reflective_loader/test_reflective_loader.dart';
 
 import 'scanner_test.dart';
 
 main() {
   defineReflectiveSuite(() {
     defineReflectiveTests(ScannerTest_Fasta);
     defineReflectiveTests(ScannerTest_Fasta_Direct);
-    defineReflectiveTests(ScannerTest_Fasta_Roundtrip);
   });
 }
 
 @reflectiveTest
 class ScannerTest_Fasta extends ScannerTestBase {
   @override
   Token scanWithListener(String source, ErrorListener listener,
       {bool genericMethodComments: false,
       bool lazyAssignmentOperators: false}) {
     var scanner = new fasta.StringScanner(source,
@@ skipping 468 matching lines @@
 /// Scanner tests that exercise the Fasta scanner directly.
 @reflectiveTest
 class ScannerTest_Fasta_Direct extends ScannerTest_Fasta_Base {
   @override
   Token scan(String source) {
     var scanner = new fasta.StringScanner(source, includeComments: true);
     return scanner.tokenize();
   }
 }
 
-/// Scanner tests that exercise the Fasta scanner, then convert the tokens to
-/// analyzer tokens, then convert back to Fasta tokens before checking
-/// assertions.
-@reflectiveTest
-class ScannerTest_Fasta_Roundtrip extends ScannerTest_Fasta_Base {
-  @override
-  Token scan(String source) {
-    var scanner = new fasta.StringScanner(source, includeComments: true);
-    var fastaTokenStream = scanner.tokenize();
-    var analyzerTokenStream = new ToAnalyzerTokenStreamConverter_NoErrors()
-        .convertTokens(fastaTokenStream);
-    return fromAnalyzerTokenStream(analyzerTokenStream);
-  }
-}
-
 /// Override of [ToAnalyzerTokenStreamConverter] that verifies that there are no
 /// errors.
 class ToAnalyzerTokenStreamConverter_NoErrors
     extends ToAnalyzerTokenStreamConverter {
   @override
   void reportError(
       ScannerErrorCode errorCode, int offset, List<Object> arguments) {
     fail('Unexpected error: $errorCode, $offset, $arguments');
   }
 }
 
 /// Override of [ToAnalyzerTokenStreamConverter] that records errors in an
 /// [ErrorListener].
 class ToAnalyzerTokenStreamConverter_WithListener
     extends ToAnalyzerTokenStreamConverter {
   final ErrorListener _listener;
 
   ToAnalyzerTokenStreamConverter_WithListener(this._listener);
 
   @override
   void reportError(
       ScannerErrorCode errorCode, int offset, List<Object> arguments) {
     _listener.errors.add(new TestError(offset, errorCode, arguments));
   }
 }