Add Timer implementation for dart2js. Also moves tests to appropriate location.

lib/isolate/dart2js/timer_provider.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.
+
+
+// We don't want to import the DOM library just because of window.setTimeout,
+// so we reconstruct the Window class here. The only conflict that could happen
+// with the other DOMWindow class would be because of subclasses.
+// Currently, none of the two Dart classes have subclasses.
+typedef void _TimeoutHandler();
+
+class _Window native "@*DOMWindow" {
+  int setTimeout(_TimeoutHandler handler, int timeout) native;
+  int setInterval(_TimeoutHandler handler, int timeout) native;
+}
+
+_Window get _window() native

[kasperl, 2012/08/09 06:15:33]

Could this be using the JS helper rather than being a native method? Long term,
we're much more likely to be able to inline proper Dart method that use the JS
helper.

[Siggi Cherem (dart-lang), 2012/08/09 20:37:14]

Done.

+    "return typeof window != 'undefined' ? window : (void 0);";
+
+class _Timer implements Timer {
+  bool _once;

[kasperl, 2012/08/09 06:15:33]

It seems perfectly possible to make both fields final.

[Siggi Cherem (dart-lang), 2012/08/09 20:37:14]

Done for '_once'.

Can't do it for _handle, though - because I need to create a closure in order to
call setTimeout. The closure creation is not allowed in the initializer block.

The vm checks that final fields are initialized in initializers (outside of the
ctor body), but it seems that dart2js is not doing so right now.

+  int _handle;
+
+  _Timer(int milliSeconds, void callback(Timer timer))
+      : _once = true {
+    _handle = _window.setTimeout(() => callback(this), milliSeconds);
+  }
+
+  _Timer.repeating(int milliSeconds, void callback(Timer timer))
+      : _once = false {
+    _handle = _window.setInterval(() => callback(this), milliSeconds);
+  }
+
+  void cancel() {
+    if (_once) {
+      _window.clearTimeout(_handle);
+    } else {
+      _window.clearInterval(_handle);
+    }
+  }
+}
+
+Timer _timerFactory(int millis, void callback(Timer timer), bool repeating) {
+  if (repeating) {

[kasperl, 2012/08/09 06:15:33]

Maybe use ?:.

[Siggi Cherem (dart-lang), 2012/08/09 20:37:14]

Done.

+    return new _Timer.repeating(millis, callback);
+  } else {
+    return new _Timer(millis, callback);
+  }
+}