<AWT Dev> RFR: 8226806 [macOS 10.14] Methods of Java Robot should be called from appropriate thread

[Sergey Bylokhov]

Hello.
Please review the fix for jdk/client.

Bug: https://bugs.openjdk.java.net/browse/JDK-8226806
Fix: http://cr.openjdk.java.net/~serb/8226806/webrev.00

On macOS 10.14(and not on 10.13/10.15) some of the Robot
operations produce the warnings in the error log which
suggests that the used API should be called on Appkit thread only.

Some related information can be found here:
     https://indiestack.com/2018/08/let-it-rip/

The root cause in the case of Robot is the generation of
keyboard events. To fix that, I have moved these methods to the
Appkit, even mouse events to prevent races between event generations.

-- 
Best regards, Sergey.