Update the versions of several `devDependencies` in `package.json`. `grunt-cssjanus` has been updated to `0.2.2`, we no longer need the fork. Run `npm install` to receive updates for `node_modules` in the project root.

Props yoavf, TobiasBg.
Fixes #26073.



git-svn-id: https://develop.svn.wordpress.org/trunk@27053 602fd350-edb4-49c9-b593-d223f7449a82
Ignore `.js` files in `wp-content` when running `jsvalidate` during `grunt build`. See [26977].

Props TobiasBg.
Fixes #26615.



git-svn-id: https://develop.svn.wordpress.org/trunk@27054 602fd350-edb4-49c9-b593-d223f7449a82