Added minimal documentation to the KeyboardEvent class.

sdk/lib/html/dart2js/html_dart2js.dart

Index: sdk/lib/html/dart2js/html_dart2js.dart
diff --git a/sdk/lib/html/dart2js/html_dart2js.dart b/sdk/lib/html/dart2js/html_dart2js.dart
index 116b28dfc19ca1a2e022b59ab0224e24c0580572..279cf911761c9b44e5c9c2e15782ce3381393148 100644
--- a/sdk/lib/html/dart2js/html_dart2js.dart
+++ b/sdk/lib/html/dart2js/html_dart2js.dart
@@ -13457,6 +13457,15 @@ class InputMethodContext native "InputMethodContext" {
 // BSD-style license that can be found in the LICENSE file.
 
 
+/**
+ * An event that describes user interaction with the keyboard.
+ *
+ * The [type] of the event identifies what kind of interaction occurred.
+ *
+ * See also:
+ *
+ * * [KeyboardEvent](https://developer.mozilla.org/en/DOM/KeyboardEvent) at MDN.
+ */
 @DomName('KeyboardEvent')
 class KeyboardEvent extends UIEvent native "KeyboardEvent" {