Test bug fix review request.

[Andrey Rusakov]

Hi everyone.
Please take a look at my fix for openjfx test: JDK-8157589 
<https://bugs.openjdk.java.net/browse/JDK-8157589>, webrev: 8157589/ 
<http://cr.openjdk.java.net/%7Earusakov/8157589/webrev.00/>

With best regards, Andrew.