changed travis file

Author: Wenish

.travis.yml

@@ -28,9 +28,8 @@ install:
 - curl -o- -L https://yarnpkg.com/install.sh | bash
 - source ~/.bashrc
 - npm install -g xvfb-maybe
-- yarn
 script:
-- yarn run build
+- npm run build
 branches:
   only:
   - master