Issue #2853503 by Aki Tendo, alexpott, larowlan, Wim Leers, klausi, fgm, dawehner, mondrake, catch, Berdir, neclimdul, borisson_: Remove all assert('string') calls from Drupal core because deprecated in PHP 7.2

Issue #2901562 by mfernea, Jo Fitzgerald, Yogesh Pawar, 3ssom, Mile23, borisson_: Fix 'Squiz.WhiteSpace.SuperfluousWhitespace' coding standard

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

Issue #2853509 by alexpott, xjm, nod_, dmsmidt, dawehner, catch, graber: Don't render status messages if there are no messages but also include their assets if there might be

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 #2712647 by slasher13, klausi, catch, jibran, Manuel Garcia, alexpott, mpdonadio, naveenvalecha, neclimdul, timmillwood, webflo, dawehner, Wim Leers, pounard: Update Symfony components to ~3.2

Issue #2854529 by alexpott, xjm, klausi, Chi, Mixologic: Fix Drupal.Scope.MethodScope - all methods should have scopes

Issue #2803779 by pfrenssen, klausi, Mile23, alexpott, dawehner: Update Coder to 8.2.10 and fix errors from improved sniffs

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 #2835604 by Wim Leers, effulgentsia: BigPipe provides functionality, not an API: mark all classes & interfaces @internal

Revert "Issue #2712647 by klausi, catch, slasher13, jibran, Manuel Garcia, alexpott, naveenvalecha, neclimdul, dawehner, Wim Leers, pounard: Update Symfony components to ~3.1"

This reverts commit a55b8ef1.

Issue #2712647 by klausi, catch, slasher13, jibran, Manuel Garcia, alexpott, naveenvalecha, neclimdul, dawehner, Wim Leers, pounard: Update Symfony components to ~3.1

Issue #2567715 by marthinal, hgoto, jpd4nt, mr.baileys, Wim Leers, alexpott: #markup generated by #pre_render callbacks do not get processed by ensureMarkupIsSafe()

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 #2678662 by Wim Leers, mondrake, Fabianx, alexpott: Ensure BigPipe does not break when HTML document contains CDATA sections or inline scripts matching certain patterns

Issue #2752413 by danmuzyka, alexpott, jhedstrom: Custom CSS classes added to status messages print on page as content when using Classy theme or subthemes

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 #2719695 by alexpott, Mile23: Fix 'Drupal.Classes.ClassDeclaration.CloseBraceAfterBody' coding standard

Issue #2572777 by andypost, alexpott, attiks, andriyun: Fix 'Squiz.Strings.ConcatenationSpacing' coding standard

Issue #2702609 by Wim Leers, Berdir, Fabianx: Disable placeholdering (and BigPipe) on unsafe requests to help find forms as fast as possible (to allow EnforcedResponses to work)

Issue #2702001 by olafkarsten, Wim Leers: Inject config factory for BigPipe (including in exception handlers)

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