Added helpful information on all event getters and static members.

tools/dom/templates/html/impl/impl_Element.darttemplate

 // 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 $LIBRARYNAME;
 
 class _ChildrenElementList extends ListBase<Element>
     implements NodeListWrapper {
   // Raw Element.
   final Element _element;
@@ skipping 810 matching lines @@
         this._scrollIntoViewIfNeeded(true);
       } else {
         this._scrollIntoViewIfNeeded();
       }
     } else {
       this._scrollIntoView();
     }
   }
 
 $if DART2JS
+  /**
+   * Static factory designed to expose `mousewheel` events to event
+   * handlers that are not necessarily instances of [Element].
+   *
+   * See [EventStreamProvider] for usage information.
+   */
   @DomName('Element.mouseWheelEvent')
   static const EventStreamProvider<WheelEvent> mouseWheelEvent =
       const _CustomEventStreamProvider<WheelEvent>(
         Element._determineMouseWheelEventType);
 
   static String _determineMouseWheelEventType(EventTarget e) {
     if (JS('bool', '#.onwheel !== undefined', e)) {
       // W3C spec, and should be IE9+, but IE has a bug exposing onwheel.
       return 'wheel';
     } else if (JS('bool', '#.onmousewheel !== undefined', e)) {
       // Chrome & IE
       return 'mousewheel';
     } else {
       // Firefox
       return 'DOMMouseScroll';
     }
   }
 
+  /**
+   * Static factory designed to expose `transitionend` events to event
+   * handlers that are not necessarily instances of [Element].
+   *
+   * See [EventStreamProvider] for usage information.
+   */
   @DomName('Element.transitionEndEvent')
   static const EventStreamProvider<TransitionEvent> transitionEndEvent =
       const _CustomEventStreamProvider<TransitionEvent>(
         Element._determineTransitionEventType);
 
   static String _determineTransitionEventType(EventTarget e) {
     // Unfortunately the normal 'ontransitionend' style checks don't work here.
     if (Device.isWebKit) {
       return 'webkitTransitionEnd';
     } else if (Device.isOpera) {
@@ skipping 430 matching lines @@
   const ScrollAlignment._internal(this._value);
   toString() => 'ScrollAlignment.$_value';
 
   /// Attempt to align the element to the top of the scrollable area.
   static const TOP = const ScrollAlignment._internal('TOP');
   /// Attempt to center the element in the scrollable area.
   static const CENTER = const ScrollAlignment._internal('CENTER');
   /// Attempt to align the element to the bottom of the scrollable area.
   static const BOTTOM = const ScrollAlignment._internal('BOTTOM');
 }