Implement the new '??' operator in analyzer.

pkg/analyzer/lib/src/analyzer_impl.dart

 // Copyright (c) 2013, 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 analyzer_impl;
 
 import 'dart:async';
 import 'dart:collection';
 import 'dart:io';
 
@@ skipping 193 matching lines @@
         declaredVariables.define(variableName, value);
       });
     }
     // Uncomment the following to have errors reported on stdout and stderr
     AnalysisEngine.instance.logger = new StdLogger(options.log);
 
     // set options for context
     AnalysisOptionsImpl contextOptions = new AnalysisOptionsImpl();
     contextOptions.cacheSize = _MAX_CACHE_SIZE;
     contextOptions.hint = !options.disableHints;
+    contextOptions.enableNullAwareOperators = options.enableNullAwareOperators;
     contextOptions.enableStrictCallChecks = options.enableStrictCallChecks;
     contextOptions.analyzeFunctionBodiesPredicate =
         _analyzeFunctionBodiesPredicate;
     contextOptions.generateImplicitErrors = options.showPackageWarnings;
     contextOptions.generateSdkErrors = options.showSdkWarnings;
     context.analysisOptions = contextOptions;
 
     librarySource = computeLibrarySource();
 
     Uri libraryUri = librarySource.uri;
@@ skipping 264 matching lines @@
     }
   }
 
   @override
   void logInformation2(String message, Object exception) {
     if (log) {
       stdout.writeln(message);
     }
   }
 }