Use UnaryOperator and BinaryOperator in ConstantSystem.

pkg/docgen/lib/src/models/model_helpers.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 docgen.model_helpers;
 
 import 'dart:collection';
 
 import 'package:compiler/src/constants/expressions.dart';
 
@@ skipping 83 matching lines @@
     return null;
   }
 
   @override
   Annotation visitBinary(BinaryConstantExpression exp,
                          AnnotationInfo context) {
     return null;
   }
 
   @override
+  Annotation visitIdentical(IdenticalConstantExpression exp,
+                            AnnotationInfo context) {
+    return null;
+  }
+
+  @override
   Annotation visitConcatenate(ConcatenateConstantExpression exp,
                               AnnotationInfo context) {
     return null;
   }
 
   @override
   Annotation visitConditional(ConditionalConstantExpression exp,
                               AnnotationInfo context) {
     return null;
   }
@@ skipping 247 matching lines @@
   // the time.
   var sdkLibrary = LIBRARIES[dart2js_util.nameOf(mirror)];
   if (sdkLibrary != null) {
     return !sdkLibrary.documented;
   } else if (dart2js_util.nameOf(mirror).startsWith('_') || dart2js_util.nameOf(
       mirror).contains('._')) {
     return true;
   }
   return false;
 }