Fix shake-to-reload

The Dart bindings changed syntax a bit. This CL updates shake-to-reload to
match the new names.

R=rafaelw@chromium.org

Review URL: https://codereview.chromium.org/987103003
diff --git a/sky/framework/debug/shake-to-reload.sky b/sky/framework/debug/shake-to-reload.sky
index ac0a894..2fc8bba 100644
--- a/sky/framework/debug/shake-to-reload.sky
+++ b/sky/framework/debug/shake-to-reload.sky
@@ -9,10 +9,8 @@
     SensorServiceProxy sensorService = new SensorServiceProxy.unbound();
     shell.requestService(sensorService);
 
-    _stub = new SensorListenerStub.unbound()
-            ..delegate = this;
+    _stub = new SensorListenerStub.unbound()..impl = this;
     sensorService.ptr.addListener(SensorType_ACCELEROMETER, _stub);
-    _stub.listen();
   }
 
   void onAccuracyChanged(int accuracy) {