review: [JavaFX] Conditional support for GTK 3 on Linux

[David Hill]

Kevin, Phil,

https://bugs.openjdk.java.net/browse/JDK-8087516
[JavaFX] Conditional support for GTK 3 on Linux

Here is the latest version of the changes.
This addresses the issues raised by Kevin, as well as some other minor cleanups.
This passes a FULL_TEST and Robot manual tests with GTK 2 & 3 for me.

http://cr.openjdk.java.net/~ddhill/8087516.2/

-- 
David Hill<David.Hill at Oracle.com>
Java Embedded Development

"A man's feet should be planted in his country, but his eyes should survey the world."
-- George Santayana (1863 - 1952)