Drop linting of the .eslintrc.js config files.
Fix some minor errors in the code (missing let/const, undefined vars).
Let eslint know that some files get their globals from other places (typically via xul script tags).
MozReview-Commit-ID: CwxuwPtRUr6
--HG--
rename : browser/components/contextualidentity/test/browser/.eslintrc.js => browser/components/syncedtabs/test/browser/.eslintrc.js
rename : browser/components/contextualidentity/test/browser/.eslintrc.js => browser/extensions/webcompat/test/browser/.eslintrc.js
extra : rebase_source : 9026aac49953d941853022cbab3e33d7d2f2fa21
Brian Grinstead
Mark Banner
Matthew Noorenberghe