fix fasta scanner adapter lineStarts

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/fasta_codes.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;
@@ skipping 483 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();
   }
 
+  void test_linestarts() {
+    var scanner = new fasta.StringScanner("var\r\ni\n=\n1;\n");
+    var token = scanner.tokenize();
+    expect(token.lexeme, 'var');
+    var lineStarts = scanner.lineStarts;
+    expect(lineStarts, orderedEquals([0, 5, 7, 9, 12, 13]));
+  }
+
   test_unterminated_string_with_unterminated_interpolation() {
     Token token = scan(r'"foo ${bar');
     BeginToken interpolationStart = token.next;
 
     Token previous;
     while (token.kind != fasta.BAD_INPUT_TOKEN) {
       expect(token.isEof, isFalse);
       previous = token;
       token = token.next;
     }
@@ skipping 32 matching lines @@
   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));
   }
 }