[8] Review request for 8000423 Diacritic is not applyed to a base letter on Linux

[Alexander Scherbatiy]

bug: http://bugs.sun.com/bugdatabase/view_bug.do?bug_id=8000423
webrev: http://cr.openjdk.java.net/~alexsch/8000423/webrev.00/
This is a regression from the issue 7146572 enableInputMethod(false) 
does not work in the TextArea and TextField on the linux platform:
   http://hg.openjdk.java.net/jdk8/awt/jdk/rev/04bc6f65d9ce
The input method enabling has been removed from the peer classes for the 
TextField and TextArea. Becuase of it the input methods are disbaled now 
by default.

The fix enables the input methods in the XToolkit.

Thanks,
Alexandr.