Switch to using HashChangeEvent constructor instead of initHashChangeEvent

sdk/lib/html/dart2js/html_dart2js.dart

Index: sdk/lib/html/dart2js/html_dart2js.dart
diff --git a/sdk/lib/html/dart2js/html_dart2js.dart b/sdk/lib/html/dart2js/html_dart2js.dart
index 883ae88ff1caaa01e4fb046abc37f08ea4f1ee66..a9506eaa3798aea12d8fd05d2066d9ea2d03f829 100644
--- a/sdk/lib/html/dart2js/html_dart2js.dart
+++ b/sdk/lib/html/dart2js/html_dart2js.dart
@@ -17688,10 +17688,17 @@ class HashChangeEvent extends Event {
   factory HashChangeEvent(String type,
       {bool canBubble: true, bool cancelable: true, String oldUrl,
       String newUrl}) {
-    var event = document._createEvent("HashChangeEvent");
-    event._initHashChangeEvent(type, canBubble, cancelable, oldUrl, newUrl);
-    return event;
+
+    var options = {
+      'canBubble' : canBubble,
+      'cancelable' : cancelable,
+      'oldURL': oldUrl,
+      'newURL': newUrl,
+    };
+    return JS('HashChangeEvent', 'new HashChangeEvent(#, #)',
+        type, convertDartToNative_Dictionary(options));
   }
+
   // To suppress missing implicit constructor warnings.
   factory HashChangeEvent._() { throw new UnsupportedError("Not supported"); }