Fix static-ness of const fields in timer.

tools/dom/src/native_DOMImplementation.dart

 // Copyright (c) 2012, 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.
 
 part of html;
 
 class _ConsoleVariables {
   Map<String, Object> _data = new Map<String, Object>();
 
   /**
@@ skipping 513 matching lines @@
 final _forwardingPrintClosure = _Utils.forwardingPrint;
 
 final _uriBaseClosure = () => Uri.parse(window.location.href);
 
 final _pureIsolateUriBaseClosure = () {
   throw new UnimplementedError("Uri.base on a background isolate "
                                "is not supported in the browser");
 };
 
 class _Timer implements Timer {
-  const int _STATE_TIMEOUT = 0;
-  const int _STATE_INTERVAL = 1;
-  var _state;
+  static const int _STATE_TIMEOUT = 0;
+  static const int _STATE_INTERVAL = 1;
+  int _state;
 
   _Timer(int milliSeconds, void callback(Timer timer), bool repeating) {
     if (repeating) {
-      _state = window._setInterval(() {
+      _state = (window._setInterval(() {
         callback(this);
-      }, milliSeconds) * 2 + _STATE_INTERVAL;
+      }, milliSeconds) << 1) | _STATE_INTERVAL;
     } else {
-      _state = window._setTimeout(() {
+      _state = (window._setTimeout(() {
         _state = null;
         callback(this);
-      }, milliSeconds) * 2 + _STATE_TIMEOUT;
+      }, milliSeconds) << 1) | _STATE_TIMEOUT;
     }
   }
 
   void cancel() {
     if (_state == null) return;
-    int id = _state ~/ 2;
+    int id = _state >> 1;
     if ((_state & 1) == _STATE_TIMEOUT) {
       window._clearTimeout(id);
     } else {
       window._clearInterval(id);
     }
     _state = null;
   }
 
   bool get isActive => _state != null;
 }
@@ skipping 48 matching lines @@
   _scheduleImmediateHelper._schedule(callback);
 };
 
 get _pureIsolateScheduleImmediateClosure => ((void callback()) =>
   throw new UnimplementedError("scheduleMicrotask in background isolates "
                                "are not supported in the browser"));
 
 void _initializeCustomElement(Element e) {
   _Utils.initializeCustomElement(e);
 }