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

client/html/generated/html/dartium/InputElement.dart

Index: client/html/generated/html/dartium/InputElement.dart
diff --git a/client/html/generated/html/dartium/InputElement.dart b/client/html/generated/html/dartium/InputElement.dart
index e550354b8f4a112845b4202516f2afda66166e7d..aa59e4765a3bd4e909513e0c04f9f1ffcdfcd7bc 100644
--- a/client/html/generated/html/dartium/InputElement.dart
+++ b/client/html/generated/html/dartium/InputElement.dart
@@ -2,6 +2,11 @@
 class _InputElementImpl extends _ElementImpl implements InputElement {
   _InputElementImpl._wrap(ptr) : super._wrap(ptr);
 
+  _InputElementEventsImpl get on() {
+    if (_on == null) _on = new _InputElementEventsImpl(this);
+    return _on;
+  }
+
   String get accept() => _wrap(_ptr.accept);
 
   void set accept(String value) { _ptr.accept = _unwrap(value); }
@@ -170,11 +175,6 @@ class _InputElementImpl extends _ElementImpl implements InputElement {
 
   bool get willValidate() => _wrap(_ptr.willValidate);
 
-  _InputElementEventsImpl get on() {
-    if (_on == null) _on = new _InputElementEventsImpl(this);
-    return _on;
-  }
-
   bool checkValidity() {
     return _wrap(_ptr.checkValidity());
   }