[9] Review request for 8036819, JAB: mnemonics not read for textboxes

[Vivi An]

Hello,

Could you please review the fix for JDK 9?
This bug is JAB related.  Mnemonics not read for textbox. Fix made uses 
the available (linked) JLabel in JComponent to get available accessible 
key binding info.

Bug: https://bugs.openjdk.java.net/browse/JDK-8036819
Webrev: http://cr.openjdk.java.net/~asaha/8036819/webrev.00/

Thanks

~ Vivi