Issue #2894269 by droplet, Akram Khan, _pratik_, dylf, nod_, Cottser: `bool` in JSDoc should be `boolean`

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

Issue #3101543 by lauriii, bnjmnm, ravi.shankar, alexpott: Update core JavaScript dependencies listed in package.json

Revert "Issue #3101543 by lauriii, bnjmnm, ravi.shankar: Update core JavaScript dependencies listed in package.json"

This reverts commit 2dadb738.

Issue #3101543 by lauriii, bnjmnm, ravi.shankar: Update core JavaScript dependencies listed in package.json

Issue #2542050 by droplet, nod_, dpacassi, Wim Leers, Sam152, andrewmacpherson, tameeshb, jonathanshaw, lokapujya, Daniel Schaefer, Chi, geerlingguy, tarekdj: Toolbar implementation creates super annoying re-rendering

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

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