Aligned Travis configuration after switching to Yarn. See ckeditor/ck…

…editor5#1214.

.travis.yml

@@ -4,30 +4,29 @@ addons:
   firefox: latest
   apt:
     sources:
-    - google-chrome
+      - google-chrome
     packages:
-    - google-chrome-stable
+      - google-chrome-stable
 language: node_js
 node_js:
-- '8'
+  - '8'
 cache:
-- node_modules
+  yarn: true
 branches:
-   except:
-   - stable
+  except:
+    - stable
 before_install:
-- export DISPLAY=:99.0
-- sh -e /etc/init.d/xvfb start
-- npm config set package-lock false
-- npm i -g npm@^5.7.1
+  - 'export DISPLAY=:99.0'
+  - sh -e /etc/init.d/xvfb start
+  - npm i -g yarn
 install:
-- npm install @ckeditor/ckeditor5-dev-tests
-- ckeditor5-dev-tests-install-dependencies
+  - yarn add @ckeditor/ckeditor5-dev-tests
+  - ckeditor5-dev-tests-install-dependencies
 script:
-- ckeditor5-dev-tests-travis
+  - ckeditor5-dev-tests-travis
 after_success:
-- ckeditor5-dev-tests-save-revision
+  - ckeditor5-dev-tests-save-revision
 env:
   global:
-  - secure: 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
-  - secure: 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
+    - secure: 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
+    - secure: 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