update fasta scanner to always generate INDEX or INDEX_EQ tokens

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:front_end/src/fasta/analyzer/token_utils.dart';
 import 'package:front_end/src/fasta/scanner/error_token.dart' as fasta;
 import 'package:front_end/src/fasta/scanner/keyword.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 139 matching lines @@
 
   @override
   @failingTest
   void test_comment_generic_method_type_list() {
     // TODO(paulberry,ahe): Fasta doesn't support generic method comment syntax.
     super.test_comment_generic_method_type_list();
   }
 
   @override
   @failingTest
-  void test_index() {
-    // TODO(paulberry,ahe): "[]" should be parsed as a single token.
-    // See dartbug.com/28665.
-    super.test_index();
-  }
-
-  @override
-  @failingTest
-  void test_index_eq() {
-    // TODO(paulberry,ahe): "[]=" should be parsed as a single token.
-    // See dartbug.com/28665.
-    super.test_index_eq();
-  }
-
-  @override
-  @failingTest
   void test_mismatched_closer() {
     // TODO(paulberry,ahe): Fasta and analyzer recover this error differently.
     // Figure out which recovery technique we want the front end to use.
     super.test_mismatched_closer();
   }
 
   @override
   @failingTest
   void test_mismatched_opener() {
     // TODO(paulberry,ahe): Fasta and analyzer recover this error differently.
@@ skipping 289 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));
   }
 }