Moved most of html lib generating scripts into tools.

sdk/lib/html/templates/html/dart2js/impl_ElementEvents.darttemplate

Index: sdk/lib/html/templates/html/dart2js/impl_ElementEvents.darttemplate
diff --git a/sdk/lib/html/templates/html/dart2js/impl_ElementEvents.darttemplate b/sdk/lib/html/templates/html/dart2js/impl_ElementEvents.darttemplate
deleted file mode 100644
index 6ca992f97ea782b0edc4bb05edeaaf46c9756c0f..0000000000000000000000000000000000000000
--- a/sdk/lib/html/templates/html/dart2js/impl_ElementEvents.darttemplate
+++ /dev/null
@@ -1,22 +0,0 @@
-// Copyright (c) 2012, the Dart project authors.  Please see the AUTHORS file
-// for details. All rights reserved. Use of this source code is governed by a
-// BSD-style license that can be found in the LICENSE file.
-
-part of html;
-
-class $CLASSNAME extends $SUPER {
-  $CLASSNAME(EventTarget _ptr) : super(_ptr);
-$!MEMBERS
-  EventListenerList get mouseWheel {
-    if (JS('bool', '#.onwheel !== undefined', _ptr)) {
-      // W3C spec, and should be IE9+, but IE has a bug exposing onwheel.
-      return this['wheel'];
-    } else if (JS('bool', '#.onmousewheel !== undefined', _ptr)) {
-      // Chrome & IE
-      return this['mousewheel'];
-    } else {
-      // Firefox
-      return this['DOMMouseScroll'];
-    }
-  }
-}