This test consistently fails for me on Linux:

StraightLineTest > testLine FAILED
    org.junit.ComparisonFailure: expected:<rgba([0,0,0],255)> but was:<rgba([18,0,19],255)>
        at org.junit.Assert.assertEquals(Assert.java:117)
        at org.junit.Assert.assertEquals(Assert.java:146)
        at test.javafx.scene.web.StraightLineTest.lambda$testLine$5(StraightLineTest.java:173)

We should probably skip this test on Linux until it is fixed, so I'll file a bug to do that.