Intermittent timeout in /_webgl/conformance/glsl/bugs/temp-expressions-should-not-crash.html

```
  ▶ TIMEOUT [expected OK] /_webgl/conformance/glsl/bugs/complex-glsl-does-not-crash.html
  │ 
  │ VMware, Inc.
  │ softpipe
  └ 3.3 (Core Profile) Mesa 18.3.0-devel

  ▶ Unexpected subtest result in /_webgl/conformance/glsl/bugs/complex-glsl-does-not-crash.html:
  └ NOTRUN [expected PASS] Overall test
```