[7u] Request for review and approval/backport: 7189299: DefaultButtonModel instance keeps stale listeners of JButton in case of multiple SwingUtilities.updateComponentTreeUI() calls

[Frank Ding]

Hi all,

   I'd like to request for approval to push the following change into 
7u.  The patch in 7u is exactly identical to the one in 8.

Bug: http://bugs.sun.com/bugdatabase/view_bug.do?bug_id=7189299 (the 
link is not available)

Changeset in jdk8
http://hg.openjdk.java.net/jdk8/awt/jdk/rev/4bf242def958
Reviewed by alexsch, malenkov

Webrev for 7u
http://cr.openjdk.java.net/~dingxmin/jdk7u/7189299/webrev.00/

Starting email discussion thread
http://mail.openjdk.java.net/pipermail/swing-dev/2012-August/002182.html

Best regards,
Frank