Add support for assert statements with messages to the analyzer.

pkg/analyzer/lib/src/generated/incremental_resolution_validator.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 engine.incremental_resolution_validator;
 
 import 'package:analyzer/src/generated/ast.dart';
 import 'package:analyzer/src/generated/element.dart';
 
 /**
@@ skipping 45 matching lines @@
     AsExpression other = this.other;
     _visitExpression(node, other);
     _visitNode(node.expression, other.expression);
     _visitNode(node.type, other.type);
   }
 
   @override
   visitAssertStatement(AssertStatement node) {
     AssertStatement other = this.other;
     _visitNode(node.condition, other.condition);
+    _visitNode(node.message, other.message);
   }
 
   @override
   visitAssignmentExpression(AssignmentExpression node) {
     AssignmentExpression other = this.other;
     _visitExpression(node, other);
     _verifyElement(node.staticElement, other.staticElement);
     _verifyElement(node.propagatedElement, other.propagatedElement);
     _visitNode(node.leftHandSide, other.leftHandSide);
     _visitNode(node.rightHandSide, other.rightHandSide);
@@ skipping 853 matching lines @@
    *     package:project/my_lib.dart      -> my_lib.dart
    */
   static String _getShortElementLocationUri(String uri) {
     int index = uri.lastIndexOf('/');
     if (index == -1) {
       return uri;
     }
     return uri.substring(index + 1);
   }
 }