Switch on null-aware operators by default in analyzer.

pkg/analyzer/lib/src/generated/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.scanner;
 
 import 'dart:collection';
 
 import 'error.dart';
 import 'java_engine.dart';
@@ skipping 705 matching lines @@
    * empty.
    */
   int _stackEnd = -1;
 
   /**
    * A flag indicating whether any unmatched groups were found during the parse.
    */
   bool _hasUnmatchedGroups = false;
 
   /**
-   * A flag indicating whether null-aware operators ('?.', '??', and '??=')
-   * should be tokenized.
-   */
-  bool enableNullAwareOperators = false;
-
-  /**
    * Initialize a newly created scanner to scan characters from the given
    * [source]. The given character [_reader] will be used to read the characters
    * in the source. The given [_errorListener] will be informed of any errors
    * that are found.
    */
   Scanner(this.source, this._reader, this._errorListener) {
     _tokens = new Token(TokenType.EOF, -1);
     _tokens.setNext(_tokens);
     _tail = _tokens;
     _tokenStart = -1;
@@ skipping 915 matching lines @@
       return _reader.advance();
     } else {
       _appendTokenOfType(TokenType.PLUS);
       return next;
     }
   }
 
   int _tokenizeQuestion() {
     // ? ?. ?? ??=
     int next = _reader.advance();
-    if (enableNullAwareOperators && next == 0x2E) {
+    if (next == 0x2E) {
       // '.'
       _appendTokenOfType(TokenType.QUESTION_PERIOD);
       return _reader.advance();
-    } else if (enableNullAwareOperators && next == 0x3F) {
+    } else if (next == 0x3F) {
       // '?'
       next = _reader.advance();
       if (next == 0x3D) {
         // '='
         _appendTokenOfType(TokenType.QUESTION_QUESTION_EQ);
         return _reader.advance();
       } else {
         _appendTokenOfType(TokenType.QUESTION_QUESTION);
         return next;
       }
@@ skipping 988 matching lines @@
   CommentToken get precedingComments => _precedingComment;
 
   void set precedingComments(CommentToken comment) {
     _precedingComment = comment;
     _setCommentParent(_precedingComment);
   }
 
   @override
   Token copy() => new TokenWithComment(type, offset, precedingComments);
 }