Add keycode constants for open square bracket, [, and close square bracket, ].

Change-Id: I9f865bdd42e617e7e776598434a78234ad3862cc
Review-Link: https://gwt-review.googlesource.com/#/c/19360/
diff --git a/user/src/com/google/gwt/event/dom/client/KeyCodes.java b/user/src/com/google/gwt/event/dom/client/KeyCodes.java
index e6881ef..826ac36 100644
--- a/user/src/com/google/gwt/event/dom/client/KeyCodes.java
+++ b/user/src/com/google/gwt/event/dom/client/KeyCodes.java
@@ -437,6 +437,16 @@
   public static final int KEY_WIN_IME = 229;
 
   /**
+   * Key code for open square bracket, [.
+   */
+  public static final int KEY_OPEN_BRACKET = 219;
+
+  /**
+   * Key code for close square bracket, ].
+   */
+  public static final int KEY_CLOSE_BRACKET = 221;
+
+  /**
    * Determines if a key code is an arrow key.
    */
   public static boolean isArrowKey(int code) {