Some minor fixes caught by the bots, suppress a test that needs more investigation

tests/compiler/dart2js/parser_helper.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.
 
 library parser_helper;
 
 import "package:expect/expect.dart";
 
 import "package:compiler/src/elements/elements.dart";
 import "package:compiler/src/tree/tree.dart";
@@ skipping 46 matching lines @@
     log(new Message(errorCode, arguments, false));
   }
 
   void reportHint(Spannable node, MessageKind errorCode, [Map arguments]) {
     log(new Message(errorCode, arguments, false));
   }
 
   withCurrentElement(Element element, f()) => f();
 }
 
-Token scan(String text) => new StringScanner.fromString(text).tokenize();
+Token scan(String text) =>
+    new StringScanner.fromString(text, enableNullAwareOperators: true)
+    .tokenize();
 
 Node parseBodyCode(String text, Function parseMethod,
                    {DiagnosticListener diagnosticHandler}) {
   Token tokens = scan(text);
   if (diagnosticHandler == null) diagnosticHandler = new LoggerCanceler();
   Uri uri = new Uri(scheme: "source");
   Script script = new Script(uri, uri,new MockFile(text));
   LibraryElement library = new LibraryElementX(script);
   library.canUseNative = true;
   NodeListener listener =
@@ skipping 43 matching lines @@
   ElementListener listener = new ElementListener(compiler, unit, () => id++);
   PartialParser parser = new PartialParser(listener);
   compiler.withCurrentElement(unit, () => parser.parseUnit(tokens));
   return unit.localMembers;
 }
 
 NodeList fullParseUnit(String source, {DiagnosticListener diagnosticHandler}) {
   return parseBodyCode(source, (parser, tokens) => parser.parseUnit(tokens),
                        diagnosticHandler: diagnosticHandler);
 }