We see the following failure occsaionally on our nightly Windows CI build:

test.javafx.scene.web.MiscellaneousTest > testDOMTimer FAILED
    java.lang.AssertionError: expected delta:850, actual delta:4669
        at org.junit.Assert.fail(Assert.java:91)
        at org.junit.Assert.assertTrue(Assert.java:43)
        at test.javafx.scene.web.MiscellaneousTest.testDOMTimer(MiscellaneousTest.java:224)

This would typically happen if the process is interrupted (e.g., on a heavily loaded system), so perhaps isn't too surprising.