$ gradle -PTEST_ONLY=true -PFULL_TEST=true -PUSE_ROBOT=true :systemTests:test --tests ViewPainterLeakTest --tests TooltipFXTest

ViewPainterLeakTest > testViewPainterLeak() FAILED
    java.lang.AssertionError: Content of WeakReference was not collected. content: javafx.scene.Scene@5a5338df
        at test.util.memory.JMemoryBuddy.assertCollectable(JMemoryBuddy.java:91)
        at test.com.sun.javafx.tk.quantum.ViewPainterLeakTest.testViewPainterLeak(ViewPainterLeakTest.java:106)

TooltipFXTest > testTooltipLeak() FAILED
    java.lang.AssertionError: Content of WeakReference was not collected. content: WebView@58bd1e96[styleClass=root web-view]
        at test.util.memory.JMemoryBuddy.assertCollectable(JMemoryBuddy.java:91)
        at test.robot.javafx.web.TooltipFXTest.testTooltipLeak(TooltipFXTest.java:166)

I don't know whether this is a test bug, a product bug, or an Apple bug.