gecko-dev/layout/reftests/css-gradients/radial-2d.html

<!-- This test checks that adjustment of stop positions to be non-negative
     happens after the calculation of implied stop positions -->
<div style="background: radial-gradient(100px 100px at 100px 100px, #ff0000 -50px, #ff0000, #0000ff 50px); width: 300px; height: 300px;"><br></div>