Silently handle handle eval exceptions in PolymerExpressions

pkg/polymer_expressions/example/example.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.
 
 import 'dart:html';
 
+import 'package:logging/logging.dart';
+import 'package:mdv/mdv.dart' as mdv;
 import 'package:polymer_expressions/polymer_expressions.dart';
-import 'package:mdv/mdv.dart' as mdv;
 
 import 'person.dart';
 
 main() {
   mdv.initialize();
+  new Logger('polymer_expressions').onRecord.listen((LogRecord r) {
+    print("${r.loggerName} ${r.level} ${r.message}");
+  });
+
   var john = new Person('John', 'Messerly', ['A', 'B', 'C']);
   var justin = new Person('Justin', 'Fagnani', ['D', 'E', 'F']);
   var globals = {
     'uppercase': (String v) => v.toUpperCase(),
     'people': [john, justin],
   };
 
   query('#test')
       ..bindingDelegate = new PolymerExpressions(globals: globals)
       ..model = john;
 
   query('#test2').model = john;
 }