Unit test timeout failure in ImageRace test

On one of my local test systems (Linux, but not likely system dependent) I get a fairly consistent timeout failure in the ImageRaceTest unit test where the threads don't start within the 1 second timeout.

ImageRaceTest#testImageInitializationRaceCondition

java.lang.RuntimeException: Initializer Thread[IntArgbPre.ToByteBgra Initializer,5,main] never started
at com.sun.javafx.image.impl.ImageRaceTest.forkAndJoinInitializers(ImageRaceTest.java:80)
at com.sun.javafx.image.impl.ImageRaceTest.testImageInitializationRaceCondition(ImageRaceTest.java:243)

I double-checked and we use 5 seconds in other similar tests (I had mistakenly indicated in the review that the timeouts were consistent with similar tests).