refactor(core): move facades out of core

This is part of ongoing work to make core platform-independent.

BREAKING CHANGE

All private exports from 'angular2/src/core/facade/{lang,collection,exception_handler}' should be replaced with 'angular2/src/facade/{lang,collection,exception_handler}'.

modules/angular2/src/facade/async.dart

@@ -0,0 +1,123 @@
+library angular2.core.facade.async;
+
+import 'dart:async';
+export 'dart:async' show Stream, StreamController, StreamSubscription;
+
+export 'promise.dart';
+
+class TimerWrapper {
+  static Timer setTimeout(fn(), int millis) =>
+      new Timer(new Duration(milliseconds: millis), fn);
+  static void clearTimeout(Timer timer) {
+    timer.cancel();
+  }
+
+  static Timer setInterval(fn(), int millis) {
+    var interval = new Duration(milliseconds: millis);
+    return new Timer.periodic(interval, (Timer timer) {
+      fn();
+    });
+  }
+
+  static void clearInterval(Timer timer) {
+    timer.cancel();
+  }
+}
+
+class ObservableWrapper {
+  static StreamSubscription subscribe(Stream s, Function onNext,
+      [onError, onComplete]) {
+    return s.listen(onNext,
+        onError: onError, onDone: onComplete, cancelOnError: true);
+  }
+
+  static bool isObservable(obs) {
+    return obs is Stream;
+  }
+
+  /**
+   * Returns whether `emitter` has any subscribers listening to events.
+   */
+  static bool hasSubscribers(EventEmitter emitter) {
+    return emitter._controller.hasListener;
+  }
+
+  static void dispose(StreamSubscription s) {
+    s.cancel();
+  }
+
+  static void callNext(EventEmitter emitter, value) {
+    emitter.add(value);
+  }
+
+  static void callError(EventEmitter emitter, error) {
+    emitter.addError(error);
+  }
+
+  static void callComplete(EventEmitter emitter) {
+    emitter.close();
+  }
+
+  static Stream fromPromise(Future f) {
+    return new Stream.fromFuture(f);
+  }
+
+  static Future toPromise(Stream s) {
+    return s.single;
+  }
+}
+
+class EventEmitter<T> extends Stream<T> {
+  StreamController<dynamic> _controller;
+
+  /// Creates an instance of [EventEmitter], which depending on [isAsync],
+  /// delivers events synchronously or asynchronously.
+  EventEmitter([bool isAsync = true]) {
+    _controller = new StreamController.broadcast(sync: !isAsync);
+  }
+
+  StreamSubscription listen(void onData(dynamic line),
+      {void onError(Error error), void onDone(), bool cancelOnError}) {
+    return _controller.stream.listen(onData,
+        onError: onError, onDone: onDone, cancelOnError: cancelOnError);
+  }
+
+  void add(value) {
+    _controller.add(value);
+  }
+
+  void addError(error) {
+    _controller.addError(error);
+  }
+
+  void close() {
+    _controller.close();
+  }
+}
+
+//todo(robwormald): maybe fix in ts2dart?
+class Subject<T> extends Stream<T> {
+  StreamController<dynamic> _controller;
+
+  Subject([bool isAsync = true]) {
+    _controller = new StreamController.broadcast(sync: !isAsync);
+  }
+
+  StreamSubscription listen(void onData(dynamic line),
+      {void onError(Error error), void onDone(), bool cancelOnError}) {
+    return _controller.stream.listen(onData,
+        onError: onError, onDone: onDone, cancelOnError: cancelOnError);
+  }
+
+  void add(value) {
+    _controller.add(value);
+  }
+
+  void addError(error) {
+    _controller.addError(error);
+  }
+
+  void close() {
+    _controller.close();
+  }
+}