Issue #2901726 by mfernea, gmario, finn.lewis, robertoperuzzo, rachel_norfolk: Fix 'Squiz.Functions.MultiLineFunctionDeclaration' coding standard

Issue #2572791 by Mile23, andriyun, attiks, RoSk0: Fix 'Drupal.WhiteSpace.OpenBracketSpacing' coding standard

Issue #2863607 by Lendude, naveenvalecha, Wim Leers, Jo Fitzgerald: Convert WebTestBaseTests of BigPipe to BrowserTestBase

Issue #1827854 by jamesrward, dman, superspring, joseph.olstad, legolasbo, anrikun, bceyssens, mdeletter, Damien Tournoud: W3C HTML5 Validation error with PHP array-based query-strings built with url() containing [ ] characters (eg views filters)

Issue #2657684 by Wim Leers, Fabianx, xjm, effulgentsia: Refactor BigPipe internals to allow a contrib module to extend BigPipe with the ability to stream anonymous responses and prime Page Cache for subsequent visits

Issue #2569119 by pwolanin, marvin_B8, jhedstrom, csheltonlcm, alexpott, dawehner, Fabianx, catch:  Use Crypt::hashBase64(), not hash('crc32b') or sha1 for placeholder tokens

Issue #2712935 by Wim Leers, Fabianx, catch, alexpott: Messages are not rendered last, meaning those messages set within placeholders only appear on the next request

Issue #2698811 by danmuzyka, Wim Leers, jhedstrom, Fabianx: BigPipe unnecessarily renders and sends multiple-occurrence placeholders multiple times when using JS — can cause JS errors

Issue #2665992 by alexpott, klausi, heykarthikwithu, xjm, tstoeckler: @file is not required for classes, interfaces and traits

Issue #2678568 by Wim Leers: Ensure good UX & DX even when A) rendering of placeholder fails, B) some response event subscriber fails

Revert "Issue #2678568 by Wim Leers: Ensure good UX & DX even when A) rendering of placeholder fails, B) some response event subscriber fails"

This reverts commit eee35007.

Issue #2678568 by Wim Leers: Ensure good UX & DX even when A) rendering of placeholder fails, B) some response event subscriber fails

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

Issue #2679867 by Wim Leers, mr.baileys: BigPipe causes PHP notices with JavaScript disabled on error pages

Issue #2678628 by Wim Leers: Consider removing the BigPipe no-JS cookie when JS is enabled again in a browser

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