Update .travis.yml

.travis.yml

@@ -5,7 +5,6 @@ env:
   global:
     - CI_DEPS=codecov>=2.0.5
     - CI_COMMANDS=codecov
-    - MITMWEB_DIR=web
 git:
   depth: 10000
 
@@ -13,9 +12,7 @@ matrix:
   fast_finish: true
   allow_failures:
     - language: node_js
-      node_js:
-          - "6"
-          - "iojs"
+      node_js: "node"
   include:
     - python: 3.5
       env: TOXENV=lint
@@ -54,14 +51,14 @@ matrix:
     - python: 3.5
       env: TOXENV=docs
     - language: node_js
-      node_js:
-          - "6"
-          - "iojs"
-      install: cd $MITMWEB_DIR && npm install
+      node_js: "node"
+      before_install: npm install -g yarn
+      install: cd web && yarn
       script: npm test
       cache:
+          yarn: true
           directories:
-              - $MITMWEB_DIR/node_modules
+              - web/node_modules
 
 install:
   - |