Hello world element

It's working but I got an error in the console:
```
Uncaught Error: Class 'PlayerStateImpl' has no instance setter 'name='.

NoSuchMethodError: method not found: 'name='
Receiver: Instance of 'PlayerStateImpl'
Arguments: ["Guillaume"]
Stack Trace: 
#0      Object.noSuchMethod (dart:core-patch/object_patch.dart:45)
#1      _LocalInstanceMirror._invokeSetter (dart:mirrors-patch/mirrors_impl.dart:446)
#2      _LocalInstanceMirror._setFieldSlow (dart:mirrors-patch/mirrors_impl.dart:397)
#3      _LocalInstanceMirror.setField (dart:mirrors-patch/mirrors_impl.dart:409)
#4      assign (package:polymer_expressions/eval.dart:145:24)
#5      _Binding.value= (package:polymer_expressions/polymer_expressions.dart:143:13)
#6      _Binding.value= (package:polymer_expressions/polymer_expressions.dart:144:7)
#7      _LocalInstanceMirror._invokeSetter (dart:mirrors-patch/mirrors_impl.dart:446)
#8      _LocalInstanceMirror._setFieldSlow (dart:mirrors-patch/mirrors_impl.dart:397)
#9      _LocalInstanceMirror.setField (dart:mirrors-patch/mirrors_impl.dart:409)
#10     _setObjectProperty (package:observe/src/path_observer.dart:275:24)
#11     _setObjectProperty (package:observe/src/path_observer.dart:284:45)
#12     PathObserver.value= (package:observe/src/path_observer.dart:109:27)
#13     NodeBinding.value= (package:template_binding/src/node_binding.dart:46:15)
#14     _propertyValueChanged (package:polymer/src/instance.dart:1032:11)
#15     dirtyCheckZoneSpec.wrapUnaryCallback.<anonymous closure> (package:observe/src/dirty_check.dart:127:15)
#16     _rootRunUnary (dart:async/zone.dart:730)
#17     _ZoneDelegate.runUnary (dart:async/zone.dart:462)
#18     _CustomizedZone.runUnary (dart:async/zone.dart:667)
#19     _BaseZone.runUnaryGuarded (dart:async/zone.dart:582)
#20     _BufferingStreamSubscription._sendData (dart:async/stream_impl.dart:333)
#21     _BufferingStreamSubscription._add (dart:async/stream_impl.dart:263)
#22     _SyncBroadcastStreamController._sendData.<anonymous closure> (dart:async/broadcast_stream_controller.dart:345)
#23     _BroadcastStreamController._forEachListener (dart:async/broadcast_stream_controller.dart:298)
#24     _SyncBroadcastStreamController._sendData (dart:async/broadcast_stream_controller.dart:344)
#25     _BroadcastStreamController.add (dart:async/broadcast_stream_controller.dart:228)
#26     HtmlElement&Polymer&Observable.deliverChanges (package:observe/src/observable.dart:158:17)
#27     dirtyCheckObservables (package:observe/src/dirty_check.dart:64:36)
#28     Observable.dirtyCheck (package:observe/src/observable.dart:46:52)
#29     dirtyCheckZoneSpec.enqueueDirtyCheck.<anonymous closure> (package:observe/src/dirty_check.dart:109:28)
#30     dirtyCheckZoneSpec.wrapCallback.<anonymous closure> (package:observe/src/dirty_check.dart:118:15)
#31     _rootRun (dart:async/zone.dart:723)
#32     _ZoneDelegate.run (dart:async/zone.dart:453)
#33     _CustomizedZone.run (dart:async/zone.dart:663)
#34     _BaseZone.runGuarded (dart:async/zone.dart:574)
#35     _BaseZone.bindCallback.<anonymous closure> (dart:async/zone.dart:599)
#36     _asyncRunCallbackLoop (dart:async/schedule_microtask.dart:23)
#37     _asyncRunCallback (dart:async/schedule_microtask.dart:32)
#38     _handleMutation (file:///e:/b/build/slave/dartium-win-full-stable/build/src/dart/tools/dom/src/native_DOMImplementation.dart:624)
```