Intermittent pass in /_mozilla/css/border_radius_elliptical_a.html

```
  ▶ TIMEOUT [expected PASS] /_mozilla/css/border_radius_elliptical_a.html
  │ 
  │ VMware, Inc.
  │ Gallium 0.4 on softpipe
  │ 3.3 (Core Profile) Mesa 12.0.1
  │ Shutting down the Constellation after generating an output file or exit flag specified
  │ VMware, Inc.
  │ Gallium 0.4 on softpipe
  └ 3.3 (Core Profile) Mesa 12.0.1
```