Add node 11 to CI and remove node 9

.circleci/config.yml

@@ -34,7 +34,7 @@ jobs:
   build:
     working_directory: ~/babel
     docker:
-      - image: circleci/node:10
+      - image: circleci/node:11
     steps:
       - checkout
       - restore-cache: *restore-yarn-cache

.travis.yml

@@ -1,14 +1,12 @@
 git:
-  depth: 10
+  depth: 5
 sudo: false
 language: node_js
 cache:
   yarn: true
-  directories:
-    - node_modules
 node_js:
   # We test the latest version on circleci
-  - '9'
+  - '10'
   - '8'
   - '6'
 
@@ -20,7 +18,9 @@ env:
 before_install:
   - curl -o- -L https://yarnpkg.com/install.sh | bash
 
-install: yarn --ignore-engines
+install:
+  # the `make test-ci` script runs this command already
+  - if [ "$JOB" != "test" ]; then yarn install; fi
 
 before_script:
   - 'if [ "$JOB" = "babel-parser-flow-tests" ]; then make bootstrap-flow; fi'