Bug 1620542 - Automatically fix ESLint errors in .eslintrc.js files. r=mossop

.eslintrc.js

accessible/tests/browser/.eslintrc.js

accessible/tests/mochitest/.eslintrc.js

browser/.eslintrc.js

browser/base/content/test/about/.eslintrc.js

browser/base/content/test/alerts/.eslintrc.js

browser/base/content/test/caps/.eslintrc.js

browser/base/content/test/captivePortal/.eslintrc.js

browser/base/content/test/contextMenu/.eslintrc.js

browser/base/content/test/favicons/.eslintrc.js

browser/base/content/test/forms/.eslintrc.js

browser/base/content/test/fullscreen/.eslintrc.js

browser/base/content/test/general/.eslintrc.js

browser/base/content/test/historySwipeAnimation/.eslintrc.js

browser/base/content/test/keyboard/.eslintrc.js

browser/base/content/test/menubar/.eslintrc.js

browser/base/content/test/metaTags/.eslintrc.js

browser/base/content/test/outOfProcess/.eslintrc.js

browser/base/content/test/pageActions/.eslintrc.js

browser/base/content/test/pageinfo/.eslintrc.js