<AWT Dev> RFR: 8248532: Every time I change keyboard language at my MacBook, Java crashes

[Prasanta Sadhukhan]

It seems the observer either needs to be removed when it is dealloced/destroyed (Otherwise Notification Centre would
send the notification to the destroyed object resulting in crash.)

and we need to do the below in dealloc, which solves the crash in my system.

NSNotificationCenter *nc = [NSNotificationCenter defaultCenter]; [nc removeObserver:self]

But it is not done for LWCToolkit, so I changed the observer as is being done there, to make existing @implementation
class as observer

-------------

Commit messages:
 - 8248532: Every time I change keyboard language at my MacBook, Java crashes

Changes: https://git.openjdk.java.net/jdk/pull/28/files
 Webrev: https://webrevs.openjdk.java.net/?repo=jdk&pr=28&range=00
  Issue: https://bugs.openjdk.java.net/browse/JDK-8248532
  Stats: 1 line in 1 file changed: 0 ins; 0 del; 1 mod
  Patch: https://git.openjdk.java.net/jdk/pull/28.diff
  Fetch: git fetch https://git.openjdk.java.net/jdk pull/28/head:pull/28

PR: https://git.openjdk.java.net/jdk/pull/28