An attempt to run JS tests on travis in headless Firefox

Author: barancev

.travis.yml

@@ -73,7 +73,7 @@ matrix:
     - env: CHROME=1 TASK="calcdeps" BUCK="test //javascript/atoms:atoms-chrome //javascript/selenium-atoms:selenium-atoms-chrome //javascript/selenium-core:selenium-core-chrome //javascript/webdriver:webdriver-chrome"
       <<: *java
       <<: *chrome
-    - env: MARIONETTE=1 TASK="calcdeps" BUCK="test //javascript/atoms:atoms-firefox //javascript/webdriver:webdriver-firefox //javascript/selenium-atoms:selenium-atoms-firefox //javascript/selenium-core:selenium-core-firefox"
+    - env: MARIONETTE=1 MOZ_HEADLESS=1 TASK="calcdeps" BUCK="test //javascript/atoms:atoms-firefox //javascript/webdriver:webdriver-firefox //javascript/selenium-atoms:selenium-atoms-firefox //javascript/selenium-core:selenium-core-firefox"
       <<: *java
       <<: *firefox-latest
     - env: BUCK="test legacy-firefox-test"