Implementation of null-aware operators.

pkg/compiler/lib/src/scanner/parser.dart

 // Copyright (c) 2012, 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.
 
 part of scanner;
 
 class FormalParameterType {
   final String type;
   const FormalParameterType(this.type);
   bool get isRequired => this == REQUIRED;
@@ skipping 1766 matching lines @@
           if (!allowCascades) {
             return token;
           }
           token = parseCascadeExpression(token);
         } else if (identical(tokenLevel, ASSIGNMENT_PRECEDENCE)) {
           // Right associative, so we recurse at the same precedence
           // level.
           token = parsePrecedenceExpression(token.next, level, allowCascades);
           listener.handleAssignmentExpression(operator);
         } else if (identical(tokenLevel, POSTFIX_PRECEDENCE)) {
-          if (identical(info, PERIOD_INFO)) {
+          if (identical(info, PERIOD_INFO) ||
+              identical(info, QUESTION_PERIOD_INFO)) {
             // Left associative, so we recurse at the next higher
             // precedence level. However, POSTFIX_PRECEDENCE is the
             // highest level, so we just call parseUnaryExpression
             // directly.
             token = parseUnaryExpression(token.next, allowCascades);
             listener.handleBinaryExpression(operator);
           } else if ((identical(info, OPEN_PAREN_INFO)) ||
                      (identical(info, OPEN_SQUARE_BRACKET_INFO))) {
             token = parseArgumentOrIndexStar(token);
           } else if ((identical(info, PLUS_PLUS_INFO)) ||
@@ skipping 860 matching lines @@
     }
     listener.handleContinueStatement(hasTarget, continueKeyword, token);
     return expectSemicolon(token);
   }
 
   Token parseEmptyStatement(Token token) {
     listener.handleEmptyStatement(token);
     return expectSemicolon(token);
   }
 }