Parse argument definition test expressions.

dart/lib/compiler/implementation/elements/elements.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('elements');
 
 #import('dart:uri');
 
 #import('../tree/tree.dart');
 #import('../scanner/scannerlib.dart');
@@ skipping 1492 matching lines @@
       str = 'lt';
     } else if (str === '&' || str === '&=') {
       str = 'and';
     } else if (str === '^' || str === '^=') {
       str = 'xor';
     } else if (str === '|' || str === '|=') {
       str = 'or';
     } else if (selector == const SourceString('negate')) {
       // TODO(ahe): Remove this case: Legacy support for pre-0.11 spec.
       return selector;
+    } else if (str === '?') {
+      return selector;
     } else {
       throw new Exception('Unhandled selector: ${selector.slowToString()}');
     }
     return new SourceString('operator\$$str');
   }
 
   static bool isStringSupertype(Element element, Compiler compiler) {
     LibraryElement coreLibrary = compiler.coreLibrary;
     return (element == coreLibrary.find(const SourceString('Comparable')))
         || (element == coreLibrary.find(const SourceString('Hashable')))
@@ skipping 126 matching lines @@
 
   MetadataAnnotation ensureResolved(Compiler compiler) {
     if (resolutionState == STATE_NOT_STARTED) {
       compiler.resolver.resolveMetadataAnnotation(this);
     }
     return this;
   }
 
   String toString() => 'MetadataAnnotation($value, $resolutionState)';
 }