Fixing samples/swarm test.

lib/html/templates/html/interface/interface_MouseEvent.darttemplate

Index: lib/html/templates/html/interface/interface_MouseEvent.darttemplate
diff --git a/lib/html/templates/html/interface/interface_MouseEvent.darttemplate b/lib/html/templates/html/interface/interface_MouseEvent.darttemplate
index e5629e3f14c618320a7ab1c96d5b4cb67f1e343b..28dff37cf6b683ac9e5b545da6dba331c51d1ea4 100644
--- a/lib/html/templates/html/interface/interface_MouseEvent.darttemplate
+++ b/lib/html/templates/html/interface/interface_MouseEvent.darttemplate
@@ -8,9 +8,10 @@ $!COMMENT
 abstract class $ID$EXTENDS {
 
   factory $ID(String type, Window view, int detail, int screenX, int screenY,
-      int clientX, int clientY, int button, [bool canBubble, bool cancelable,
-      bool ctrlKey, bool altKey, bool shiftKey, bool metaKey,
-      EventTarget relatedTarget]) =>
+      int clientX, int clientY, int button, [bool canBubble = true,
+      bool cancelable = true, bool ctrlKey = false, bool altKey = false,
+      bool shiftKey = false, bool metaKey = false,
+      EventTarget relatedTarget = null]) =>
       _$(ID)FactoryProvider.create$ID(
           type, view, detail, screenX, screenY,
           clientX, clientY, button, canBubble, cancelable,