travis: remove FF beta from allowed failures (webrtc#938)

also removes the npm install step -- this is already done

Author: fippo

.travis.yml

@@ -33,15 +33,13 @@ matrix:
 
   allow_failures:
     - env: BROWSER=chrome  BVER=unstable
-    - env: BROWSER=firefox BVER=beta
     - env: BROWSER=firefox BVER=nightly
 
 before_install:
   - /sbin/start-stop-daemon --start --quiet --pidfile /tmp/cucumber_xvfb_99.pid --make-pidfile --background --exec /usr/bin/Xvfb -- :99 -ac -screen 0 1600x1400x16
 
 before_script:
   - pulseaudio --start
-  - npm install
 
 script:
   - npm test