Merge pull request #2033 from QingWei-Li/update/travis

Update travis.yml

.travis.yml

 sudo: false
 language: node_js
 node_js: stable
-cache:
-  directories:
-  - $HOME/.npm
-  - $HOME/.yarn-cache
-  - node_modules
 before_install:
-- curl -o- -L https://yarnpkg.com/install.sh | bash
-- export PATH=$HOME/.yarn/bin:$PATH
 - export TRAVIS_COMMIT_MSG="[deploy] $(git log --format='%h - %B' --no-merges -n 1)"
 - export TRAVIS_COMMIT_USER="$(git log --no-merges -n 1 --format=%an)"
 - export TRAVIS_COMMIT_EMAIL="$(git log --no-merges -n 1 --format=%ae)"
-install: yarn install
-script: yarn run test
 after_success:
 - sh build/deploy-ci.sh
 - cat ./test/unit/coverage/lcov.info | ./node_modules/.bin/coveralls