Modern-ify KeyEvent handling.

tools/dom/src/dart2js_KeyEvent.dart

 /**
  * A custom KeyboardEvent that attempts to eliminate cross-browser
  * inconsistencies, and also provide both keyCode and charCode information
  * for all key events (when such information can be determined).
  *
+ * KeyEvent tries to provide a higher level, more polished keyboard event
+ * information on top of the "raw" [KeyboardEvent].
+ *
  * This class is very much a work in progress, and we'd love to get information
  * on how we can make this class work with as many international keyboards as
  * possible. Bugs welcome!
  */
 class KeyEvent implements KeyboardEvent {
   /** The parent KeyboardEvent that this KeyEvent is wrapping and "fixing". */
   KeyboardEvent _parent;
 
   /** The "fixed" value of whether the alt key is being pressed. */
   bool _shadowAltKey;
@@ skipping 18 matching lines @@
 
   /** Accessor to the underlying keyCode value is the parent event. */
   int get _realKeyCode => JS('int', '#.keyCode', _parent);
 
   /** Accessor to the underlying charCode value is the parent event. */
   int get _realCharCode => JS('int', '#.charCode', _parent);
 
   /** Accessor to the underlying altKey value is the parent event. */
   bool get _realAltKey => JS('int', '#.altKey', _parent);
 
-  /** Construct a KeyEvent with [parent] as event we're emulating. */
+  /** Construct a KeyEvent with [parent] as the event we're emulating. */
   KeyEvent(KeyboardEvent parent) {
     _parent = parent;
     _shadowAltKey = _realAltKey;
     _shadowCharCode = _realCharCode;
     _shadowKeyCode = _realKeyCode;
   }
 
+  // TODO(efortuna): If KeyEvent is sufficiently successful that we want to make
+  // it the default keyboard event handling, move these methods over to Element.
+  /** Accessor to provide a stream of KeyEvents on the desired target. */
+  static EventStreamProvider<KeyEvent> keyDownEvent =
+    new _KeyboardEventHandler('keydown');
+  /** Accessor to provide a stream of KeyEvents on the desired target. */
+  static EventStreamProvider<KeyEvent> keyUpEvent =
+    new _KeyboardEventHandler('keyup');
+  /** Accessor to provide a stream of KeyEvents on the desired target. */
+  static EventStreamProvider<KeyEvent> keyPressEvent =
+    new _KeyboardEventHandler('keypress');
+
   /** True if the altGraphKey is pressed during this event. */
   bool get altGraphKey => _parent.altGraphKey;
   bool get bubbles => _parent.bubbles;
   /** True if this event can be cancelled. */
   bool get cancelable => _parent.cancelable;
   bool get cancelBubble => _parent.cancelBubble;
   void set cancelBubble(bool cancel) {
     _parent.cancelBubble = cancel;
   }
   /** Accessor to the clipboardData available for this event. */
@@ skipping 48 matching lines @@
     throw new UnsupportedError("keyIdentifier is unsupported.");
   }
   void $dom_initKeyboardEvent(String type, bool canBubble, bool cancelable,
       Window view, String keyIdentifier, int keyLocation, bool ctrlKey,
       bool altKey, bool shiftKey, bool metaKey,
       bool altGraphKey) {
     throw new UnsupportedError(
         "Cannot initialize a KeyboardEvent from a KeyEvent.");
   }
 }