Issue #2915526 by drpal: JS codestyle: prefer-const

core/.eslintrc.passing.json

core/misc/ajax.es6.js

core/misc/ajax.js

core/misc/dialog/dialog.jquery-ui.es6.js

core/misc/dialog/dialog.jquery-ui.js

core/misc/machine-name.es6.js

core/misc/machine-name.js

core/misc/tabledrag.es6.js

core/misc/tabledrag.js

core/modules/views_ui/js/views-admin.es6.js

core/modules/views_ui/js/views-admin.js