Fixed a lot of dartanalyzer static analysis issues with the html lib.

sdk/lib/html/src/KeyboardEventController.dart

 // 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;
 
 /**
  * Works with KeyboardEvent and KeyEvent to determine how to expose information
  * about Key(board)Events. This class functions like an EventListenerList, and
  * provides a consistent interface for the Dart
@@ skipping 14 matching lines @@
    */
   List<KeyboardEvent> _keyDownList;
 
   /** The set of functions that wish to be notified when a KeyEvent happens. */
   List<Function> _callbacks;
 
   /** The type of KeyEvent we are tracking (keyup, keydown, keypress). */
   String _type;
 
   /** The element we are watching for events to happen on. */
-  EventTarget _target;
+  Element _target;
 
   // The distance to shift from upper case alphabet Roman letters to lower case.
   final int _ROMAN_ALPHABET_OFFSET = "a".charCodes[0] - "A".charCodes[0];
 
   // Instance members referring to the internal event handlers because closures
   // are not hashable.
   var _keyUp, _keyDown, _keyPress;
 
   /**
    * An enumeration of key identifiers currently part of the W3C draft for DOM3
@@ skipping 38 matching lines @@
 
   /** Named constructor to add an onKeyDown event listener to our handler. */
   KeyboardEventController.keydown(EventTarget target) {
     _KeyboardEventController(target, 'keydown');
   }
 
   /**
    * General constructor, performs basic initialization for our improved
    * KeyboardEvent controller.
    */
-  _KeyboardEventController(EventTarget target, String type) {
+  _KeyboardEventController(Element target, String type) {
     _callbacks = [];
     _type = type;
     _target = target;
     _keyDown = processKeyDown;
     _keyUp = processKeyUp;
     _keyPress = processKeyPress;
   }
 
   /**
    * Hook up all event listeners under the covers so we can estimate keycodes
@@ skipping 291 matching lines @@
       _keyDownList = _keyDownList.filter((element) => element != toRemove);
     } else if (_keyDownList.length > 0) {
       // This happens when we've reached some international keyboard case we
       // haven't accounted for or we haven't correctly eliminated all browser
       // inconsistencies. Filing bugs on when this is reached is welcome!
       _keyDownList.removeLast();
     }
     _dispatch(e);
   }
 }