Merge brabch ckeditor5/t/1214

Internal: Switched to Yarn. See ckeditor/ckeditor5#1214.

.travis.yml

@@ -11,17 +11,16 @@ language: node_js
 node_js:
 - '8'
 cache:
-- node_modules
+  yarn: true
 branches:
   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
+- npm i -g yarn
 install:
-- npm install @ckeditor/ckeditor5-dev-tests
+- yarn add @ckeditor/ckeditor5-dev-tests
 - ckeditor5-dev-tests-install-dependencies
 script:
 - ckeditor5-dev-tests-travis

package.json

@@ -31,8 +31,8 @@
     "@ckeditor/ckeditor5-basic-styles": "^10.1.0",
     "@ckeditor/ckeditor5-block-quote": "^10.1.1",
     "@ckeditor/ckeditor5-ckfinder": "^10.0.0",
-    "@ckeditor/ckeditor5-dev-utils": "^11.0.0",
-    "@ckeditor/ckeditor5-dev-webpack-plugin": "^7.0.0",
+    "@ckeditor/ckeditor5-dev-utils": "^11.0.1",
+    "@ckeditor/ckeditor5-dev-webpack-plugin": "^7.0.1",
     "@ckeditor/ckeditor5-easy-image": "^10.0.4",
     "@ckeditor/ckeditor5-editor-decoupled": "^11.0.2",
     "@ckeditor/ckeditor5-essentials": "^10.1.3",