Issue #3278415 by nod_, lauriii, catch, Wim Leers, longwave, xjm, claudiu.cristea: Remove usages of the JavaScript ES6 build step, the build step itself, and associated dev dependencies

Issue #3239123 by hooroomoo, bnjmnm, nod_: Refactor (if feasible) uses of the jQuery text function to use vanillaJS

Issue #3253148 by mherchel, longwave, ckrina, droplet: Remove IE from core's browserlist, remove non-essential CSS importing and recompile assets

Issue #2548195 by nod_, JohnAlbin, madhavvyas, sriharsha.uppuluri: Only use single quotes in JavaScript and update .eslintrc

Issue #2473947 by Cottser, davidhernandez, rachel_norfolk, rteijeiro, cilefen, alimac, akalata, YesCT, mortendk: Prefix form-item-* classes with js-

Issue #1913510 by erich_s, jibran, scresante, nod_, mitron: Core Javascript Files Not Using Standard Indentation.

Issue #731724 by larowlan, andypost, dixon_, tsvenson: Convert comment settings into a field to make them work with CMI and non-node entities.