Merge branch 'winh-frontend-tests-check-dependencies' into 'master'

Ensure that dependencies are installed before running frontend tests

See merge request gitlab-org/gitlab-ce!28236

package.json

 {
   "private": true,
   "scripts": {
+    "check-dependencies": "yarn check --integrity",
     "clean": "rm -rf public/assets tmp/cache/*-loader",
     "dev-server": "NODE_OPTIONS=\"--max-old-space-size=3584\" nodemon -w 'config/webpack.config.js' --exec 'webpack-dev-server --config config/webpack.config.js'",
     "eslint": "eslint --max-warnings 0 --report-unused-disable-directives --ext .js,.vue .",
     "eslint-fix": "eslint --max-warnings 0 --report-unused-disable-directives --ext .js,.vue --fix .",
     "eslint-report": "eslint --max-warnings 0 --ext .js,.vue --format html --output-file ./eslint-report.html --no-inline-config .",
+    "prejest": "yarn check-dependencies",
+    "jest": "jest",
     "jest-debug": "node --inspect-brk node_modules/.bin/jest --runInBand",
     "jsdoc": "jsdoc -c config/jsdocs.config.js",
+    "prekarma": "yarn check-dependencies",
     "karma": "BABEL_ENV=${BABEL_ENV:=karma} karma start --single-run true config/karma.config.js",
     "karma-coverage": "BABEL_ENV=coverage karma start --single-run true config/karma.config.js",
     "karma-start": "BABEL_ENV=karma karma start config/karma.config.js",