PipeTest.sourceBlocksOnSlowWriter/sinkBlocksOnSlowReader is flaky

[JakeWharton]

 okio.PipeTest[jvm] > sourceBlocksOnSlowWriter[jvm] FAILED
    java.lang.AssertionError: expected:<4000.0> but was:<4265.846875000047>
        at org.junit.Assert.fail(Assert.java:89)
        at org.junit.Assert.failNotEquals(Assert.java:835)
        at org.junit.Assert.assertEquals(Assert.java:555)
        at org.junit.Assert.assertEquals(Assert.java:685)
        at okio.PipeTest.assertElapsed(PipeTest.kt:356)
        at okio.PipeTest.sourceBlocksOnSlowWriter(PipeTest.kt:343)

[JakeWharton]

 okio.PipeTest[jvm] > sinkBlocksOnSlowReader[jvm] FAILED
    java.lang.AssertionError: expected:<3000.0> but was:<3484.8014589999802>
        at org.junit.Assert.fail(Assert.java:89)
        at org.junit.Assert.failNotEquals(Assert.java:835)
        at org.junit.Assert.assertEquals(Assert.java:555)
        at org.junit.Assert.assertEquals(Assert.java:685)
        at okio.PipeTest.assertElapsed(PipeTest.kt:356)
        at okio.PipeTest.sinkBlocksOnSlowReader(PipeTest.kt:171)