8153304: [TEST BUG] SceneGraphTests can't be run with aurora

[Andrey Rusakov]

Hello, everyone!
There was a problem (JDK-8153304 
<https://bugs.openjdk.java.net/browse/JDK-8153304>) that was breaking 
automated closed test running.
Please look at my small fix: 
http://cr.openjdk.java.net/~arusakov/8153304/webrev.00/ 
<http://cr.openjdk.java.net/%7Earusakov/8153304/webrev.00/>
Changeset is also applicable for openjfx 9 dev tests.

<https://bugs.openjdk.java.net/browse/JDK-8093068>