Switch on null-aware operators by default in analyzer.

pkg/analyzer/lib/src/generated/incremental_scanner.dart

 // Copyright (c) 2014, 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.
 
 library engine.incremental_scanner;
 
 import "dart:math" as math;
 
 import 'package:analyzer/src/generated/engine.dart';
 
@@ skipping 206 matching lines @@
     return token;
   }
 
   /**
    * Scan the token between the [start] (inclusive) and [end] (exclusive)
    * offsets.
    */
   Token _scanRange(int start, int end) {
     Scanner scanner = new Scanner(
         source, new CharacterRangeReader(reader, start, end), errorListener);
-    scanner.enableNullAwareOperators = _options.enableNullAwareOperators;
     return scanner.tokenize();
   }
 
   /**
    * Update the offsets of every token from the given [token] to the end of the
    * stream by adding the given [delta].
    */
   void _updateOffsets(Token token, int delta) {
     while (token.type != TokenType.EOF) {
       _tokenMap.put(token, token);
       token.offset += delta;
       Token comment = token.precedingComments;
       while (comment != null) {
         comment.offset += delta;
         comment = comment.next;
       }
       token = token.next;
     }
     _tokenMap.put(token, token);
     token.offset += delta;
   }
 }