Issue #3416141 by gorkagr, Jaypan, Wim Leers, alexpott: big_pipe.js' checkMutation() does not check if node exists before using it

Revert "Issue #3416141 by gorkagr, Jaypan, Wim Leers: big_pipe.js' checkMutation() does not check if node exists before using it"

This reverts commit 2d17900f.

Issue #3416141 by gorkagr, Jaypan, Wim Leers: big_pipe.js' checkMutation() does not check if node exists before using it

Issue #3390178 by godotislate, larowlan, catch, pixlkat, Utilvideo, rsnyd, Wim Leers, cilefen, smustgrave, fjgarlin, jakegibs617, seixas, mohithasmukh, very_random_man: big_pipe sometimes fails to load blocks

Issue #3196973 by casey, nod_, andypost, yogeshmpawar, droplet, Wim Leers, justafish, finnsky: Use Mutation observer for BigPipe replacements

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 #3294720 by abramm: The attachBehaviors() for document is only called after Big Pipe chunks are processed

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

Issue #3174884 by raman.b, alexpott, lauriii, zrpnr, nod_: Update yarn dependencies for Drupal 9.1.0

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 #2981652 by ApacheEx, corbacho, drpal, dawehner, xjm, alexpott, lauriii: Format core JavaScript using recently add Prettier

Issue #2931443 by Wim Leers, casey, zuuperman, drpal: Browser parsing race condition: JSON.parse sometimes called on partially streamed BigPipe placholder replacements, causes fatal JS error

Issue #2723705 by Wim Leers, catch: Reduce the 200ms BigPipe placeholder interval to 50ms and make it overridable

Issue #2670444 by Wim Leers: Embedded AJAX responses aren't application/json, but application/vnd.drupal-ajax

Issue #2469431 by Wim Leers, Fabianx, swentel, nod_, yched, dawehner, tstoeckler, catch, borisson_: BigPipe for auth users: first send+render the cheap parts of the page, then the expensive parts