Get rid of a lot of () for getters.

lib/html/src/DeviceMotionEventWrappingImplementation.dart

 // Copyright (c) 2011, 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.
 
 class DeviceMotionEventWrappingImplementation extends EventWrappingImplementation implements DeviceMotionEvent {
   DeviceMotionEventWrappingImplementation._wrap(ptr) : super._wrap(ptr);
 
   factory DeviceMotionEventWrappingImplementation(String type,
       [bool canBubble = true, bool cancelable = true]) {
     final e = dom.document.createEvent("DeviceMotionEvent");
     e.initEvent(type, canBubble, cancelable);
     return LevelDom.wrapDeviceMotionEvent(e);
   }
 
-  num get interval() => _ptr.interval;
+  num get interval => _ptr.interval;
 }