Refactor the event-generation code to locate it in systemhtml.py.

client/html/generated/html/interface/SVGElementInstance.dart

Index: client/html/generated/html/interface/SVGElementInstance.dart
diff --git a/client/html/generated/html/interface/SVGElementInstance.dart b/client/html/generated/html/interface/SVGElementInstance.dart
index aba1a2e20f5a9749c8dc67247795fa6bd295ec47..8d5c3c1855f286c1e69427642f813635612f430e 100644
--- a/client/html/generated/html/interface/SVGElementInstance.dart
+++ b/client/html/generated/html/interface/SVGElementInstance.dart
@@ -6,6 +6,8 @@
 
 interface SVGElementInstance extends EventTarget {
 
+  SVGElementInstanceEvents get on();
+
   final SVGElementInstanceList childNodes;
 
   final SVGElement correspondingElement;
@@ -22,8 +24,6 @@ interface SVGElementInstance extends EventTarget {
 
   final SVGElementInstance previousSibling;
 
-  SVGElementInstanceEvents get on();
-
   void _addEventListener(String type, EventListener listener, [bool useCapture]);
 
   bool _dispatchEvent(Event event);