The following recently-enabled test fails intermittently:

test.javafx.scene.web.LeakTest > testGarbageCollectability FAILED
    java.lang.AssertionError: WebView has not been GCed
        at org.junit.Assert.fail(Assert.java:91)
        at org.junit.Assert.assertTrue(Assert.java:43)
        at org.junit.Assert.assertNull(Assert.java:549)
        at test.javafx.scene.web.LeakTest.lambda$testGarbageCollectability$0(LeakTest.java:97)

In looking at the test, I see that it doesn't use the pattern of calling gc/runFinalization/sleep in a loop that is used elsewhere, which explains the instability.