Travis: use yarn cache, update node to v7.9.0 and remove git-lfs (#2060)

.travis.yml

@@ -6,9 +6,9 @@ language: node_js
 matrix:
   include:
     - os: osx
-      node_js: 7.4
+      node_js: 7.9.0
     - os: linux
-      node_js: 7.4
+      node_js: 7.9.0
       env: CC=clang CXX=clang++ npm_config_clang=1
       compiler: clang
 
@@ -26,10 +26,10 @@ addons:
       - snapd
 
 before_install:
-  - mkdir -p /tmp/git-lfs && curl -L https://github.com/github/git-lfs/releases/download/v1.2.1/git-lfs-$([ "$TRAVIS_OS_NAME" == "linux" ] && echo "linux" || echo "darwin")-amd64-1.2.1.tar.gz | tar -xz -C /tmp/git-lfs --strip-components 1 && /tmp/git-lfs/git-lfs pull
   - if [[ "$TRAVIS_OS_NAME" == "linux" ]]; then export DISPLAY=:99.0; sh -e /etc/init.d/xvfb start; sleep 3; fi
-  - if [[ "$TRAVIS_OS_NAME" == "osx" ]]; then brew update; fi
-  - if [[ "$TRAVIS_OS_NAME" == "osx" ]]; then brew install yarn; fi
+  - npm install -g yarn
+
+cache: yarn
 
 install:
   - yarn

appveyor.yml

@@ -12,7 +12,7 @@ init:
   - yarn config set msvs_version 2015 # we need this to build `pty.js`
 
 install:
-  - ps: Install-Product node 8 x64
+  - ps: Install-Product node 7.9.0 x64
   - set CI=true
   - yarn