ci(.travis): update CI config

.travis.yml

@@ -1,30 +1,43 @@
 sudo: false
+dist: trusty
 language: node_js
 branches:
   only:
     - master
-matrix:
+jobs:
   fast_finish: true
+  allow_failures:
+    - env: WEBPACK_VERSION=canary
   include:
-    - os: linux
-      node_js: "8"
-      env: WEBPACK_VERSION="3.6.0" JOB_PART=lint
-    - os: linux
-      node_js: "6"
-      env: WEBPACK_VERSION="3.6.0" JOB_PART=test
-    - os: linux
-      node_js: "4.7"
-      env: WEBPACK_VERSION="3.6.0" JOB_PART=test
-    - os: linux
-      node_js: "8"
-      env: WEBPACK_VERSION="3.6.0" JOB_PART=test
+    - &test-latest
+      stage: Webpack latest
+      node_js: 6
+      env: WEBPACK_VERSION=latest JOB_PART=test
+      script: npm run travis:$JOB_PART
+    - <<: *test-latest
+      node_js: 8
+      env: WEBPACK_VERSION=latest JOB_PART=test
+      script: npm run travis:$JOB_PART
+    - <<: *test-latest
+      node_js: 8
+      env: WEBPACK_VERSION=latest JOB_PART=lint
+      script: npm run travis:$JOB_PART
+    - stage: Webpack canary
+      before_script: npm i --no-save git://github.com/webpack/webpack.git#master
+      script: npm run travis:$JOB_PART
+      node_js: 8
+      env: WEBPACK_VERSION=canary JOB_PART=test
 before_install:
+  - 'if [[ `npm -v` != 5* ]]; then npm i -g npm@^5.0.0; fi'
   - nvm --version
   - node --version
   - npm --version
 before_script:
-  - 'if [ "$WEBPACK_VERSION" ]; then npm install webpack@^$WEBPACK_VERSION; fi'
+  - |-
+    if [ "$WEBPACK_VERSION" ]; then
+      npm i --no-save webpack@$WEBPACK_VERSION
+    fi
 script:
-  - npm run travis:$JOB_PART
+  - 'npm run travis:$JOB_PART'
 after_success:
-  - bash <(curl -s https://codecov.io/bash)
+  - 'bash <(curl -s https://codecov.io/bash)'