servo: Merge #8873 - Run unit tests in ci (from apechimp:master); r=Manishearth

Fixes #8856.

Source-Repo: https://github.com/servo/servo
Source-Revision: a4f617bf1857ab054432251839ec6785a9f015ad

servo/.travis.yml

@@ -10,6 +10,7 @@ matrix:
       dist: trusty
       script:
          - ./mach build -d --verbose
+         - ./mach test-unit
          - bash etc/ci/lockfile_changed.sh
          - bash etc/ci/manifest_changed.sh          
       cache: