[9] review request:

[Kevin Rushforth]

Jim and Alexander,

Please review the following fix to allow JFXPanel to compile (and run) 
again on JDK 9.

https://bugs.openjdk.java.net/browse/JDK-8149967
http://cr.openjdk.java.net/~kcr/8149967/webrev.00/

Note that I did not provide a fallback to the existing JDK 8 method, 
since we are going to require JDK 9 soon anyway.

Note also that there is still one more bug fix needed before we can 
compile everything with JDK 9, so this is necessary but not sufficient.

-- Kevin