[8u] RFR: 8214578: [macos] Problem with backslashes on macOS/JIS keyboard: Java ignores system settings

[Alex Kashchenko]

Hi,

Please review the parity backport of JDK-8214578:

Bug: https://bugs.openjdk.java.net/browse/JDK-8214578

Original commit: https://hg.openjdk.java.net/jdk/jdk/rev/d0bfaae2ff33

8u webrev: https://cr.openjdk.java.net/~akasko/jdk8u/8214578/webrev.00/

Patch doesn't apply cleanly because of the JDK-8148555 change that is
not in 8u, useString variable is changed to aString to workaround
this.

Testing: checked manually with an on-screen JIS keyboard that yen
symbol is shown without the change and a backslash - with the change.

-- 
-Alex