Make shake-to-reload actually work

sky/framework/debug/shake-to-reload.sky

 <script>
 import '/sky/framework/shell.dart' as shell;
 import 'dart:sky';
 import 'package:sky/services/sensors/sensors.mojom.dart';
 
-// TODO(abarth): We should factor this out into a kinemetics library.
+// TODO(abarth): We should factor this out into a kinematics library.
 class _ShakeDetector extends SensorListener {
   _ShakeDetector() {
     SensorServiceProxy sensorService = new SensorServiceProxy.unbound();
     shell.requestService(sensorService);
 
     _stub = new SensorListenerStub.unbound()
             ..delegate = this;
     sensorService.ptr.addListener(SensorType_ACCELEROMETER, _stub);
     _stub.listen();
   }
@@ skipping 17 matching lines @@
   bool isShaking = false;
   SensorListenerStub _stub;
 }
 
 _ShakeDetector _detector;
 
 void _init(_) {
   _detector = new _ShakeDetector();
 }
 </script>