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

client/html/generated/html/dartium/SVGElementInstance.dart

Index: client/html/generated/html/dartium/SVGElementInstance.dart
diff --git a/client/html/generated/html/dartium/SVGElementInstance.dart b/client/html/generated/html/dartium/SVGElementInstance.dart
index bf33594ea3c24e95b05f4379dde3b26c5833a916..0f2f3efd6b99e1b734b9af8f5b7d919d731b60ae 100644
--- a/client/html/generated/html/dartium/SVGElementInstance.dart
+++ b/client/html/generated/html/dartium/SVGElementInstance.dart
@@ -2,6 +2,11 @@
 class _SVGElementInstanceImpl extends _EventTargetImpl implements SVGElementInstance {
   _SVGElementInstanceImpl._wrap(ptr) : super._wrap(ptr);
 
+  _SVGElementInstanceEventsImpl get on() {
+    if (_on == null) _on = new _SVGElementInstanceEventsImpl(this);
+    return _on;
+  }
+
   SVGElementInstanceList get childNodes() => _wrap(_ptr.childNodes);
 
   SVGElement get correspondingElement() => _wrap(_ptr.correspondingElement);
@@ -18,11 +23,6 @@ class _SVGElementInstanceImpl extends _EventTargetImpl implements SVGElementInst
 
   SVGElementInstance get previousSibling() => _wrap(_ptr.previousSibling);
 
-  _SVGElementInstanceEventsImpl get on() {
-    if (_on == null) _on = new _SVGElementInstanceEventsImpl(this);
-    return _on;
-  }
-
   void _addEventListener(String type, EventListener listener, [bool useCapture = null]) {
     if (useCapture === null) {
       _ptr.addEventListener(_unwrap(type), _unwrap(listener));