[8u-dev] RfR: backport of JDK-8156563: JavaFX Ensemble8 media sample hang and crash

[David DeHaven]

Kevin, Alexander, please review my backport of 8156563 to 8u-dev.

Main issue:
https://bugs.openjdk.java.net/browse/JDK-8156563

Backport issue:
https://bugs.openjdk.java.net/browse/JDK-8167317

Code review:
http://cr.openjdk.java.net/~ddehaven/8156563-8u/rt.0/

-DrD-