Fixing DOM's EventStream.isBroadcast

tests/html/streams_test.dart

 library streams_test;
 import '../../pkg/unittest/lib/unittest.dart';
 import '../../pkg/unittest/lib/html_config.dart';
 import 'dart:async';
 import 'dart:html';
 
 class StreamHelper {
   var _a;
   StreamHelper() {
     _a = new TextInputElement();
@@ skipping 18 matching lines @@
 
     var callCount = 0;
     helper.stream.listen((Event e) {
       ++callCount;
     });
 
     helper.pulse();
     expect(callCount, 1);
   });
 
+  test('broadcast', () {
+    var stream = new DivElement().onClick;
+    expect(stream.asBroadcastStream(), stream);
+    expect(stream.isBroadcast, isTrue);
+  });
+
   // Validates that capturing events fire on parent before child.
   test('capture', () {
     var parent = new DivElement();
     document.body.append(parent);
 
     var helper = new StreamHelper();
     parent.append(helper.element);
 
     var childCallCount = 0;
     var parentCallCount = 0;
@@ skipping 221 matching lines @@
   });
 
   test('singleMatching', () {
     stream.singleMatching((_) => true).then((_) {});
   });
 
   test('elementAt', () {
     stream.elementAt(0).then((_) {});
   });
 }