Issue #2238217 by effulgentsia, neclimdul, martin107, tim.plunkett, cweagans, kim.pepper, xjm: Introduce a RouteMatch class.

Issue #2124957 by Wim Leers, catch: Replace 'content' cache tag with 'rendered' and use it sparingly.

Issue #2246665 by jaredsmith, martin107, YesCT, filijonka, tstoeckler: Typehint with Drupal\Core\Language\LanguageInterface instead Drupal\Core\Language\Language.

Issue #2214209 by dawehner, ParisLiakos, xjm: Move _menu_site_is_offine() into the Maintainance subscriber.

Issue #2271025 by Wim Leers: Don't let menu_navigation_links() set the active class, the drupal.active-links library does that for us (plus, it's setting it incorrectly).

Issue #2183113 by jhodgdon, effulgentsia, tim.plunkett, herom, larowlan: Update hook_help signature to use route_name instead of path.

Issue #2243549 by agerson, cs_shadow | jhodgdon: Text changes needed as follow-up to Menu UI module rename.

Issue #2241655 by tim.plunkett: EntityStorageInterface::create() should always create a "new" entity.

This reverts commit 07f63fe6.

Issue #2226903 by pwolanin, dawehner, tvn, martin107, jessebeach: Step 1: Move static menu links to yml files.

Issue #2044367 by InternetDevels, Berdir, wildflower_0002, ianthomas_uk, ParisLiakos, Xano | cosmicdreams: Replace calls to lock() with \Drupal::lock().

Issue #2070369 by herom, bdgreen, Mac_Weber, InternetDevels, sidharthap, JeroenT: Remove all calls to deprecated function language().

Issue #2045927 by herom, martin107, ianthomas_uk, Xano, michaellander, Sutharsan: Replace all drupal_alter() deprecated function calls.

Issue #2198343 by damiankloip, longwave: Convert all usages of cache() and cache_invalidate_tags() procedural functions.

Issue #2179083 by Wim Leers, vijaycs85: Rendered menus (e.g. menu blocks) should set cache tags to inform the page cache.

Issue #2045931 by Sam152, joelpittet, LinL, Sutharsan, adsw12: Replace all module_exists() deprecated function calls.

Issue #1939064 by joelpittet, pwieck, farrington, mark.labrecque, Cottser, InternetDevels, mdrummond, drupalninja99, BarisW, jenlampton: Convert theme_links() to Twig.

Issue #2185831 by tim.plunkett: Split up ParamConverterManager and stop throwing NotFoundHttpException.

Issue #2047633 by pwolanin, dawehner, kim.pepper, Xano, amateescu, tim.plunkett: Move definition of menu links to hook_menu_link_defaults(), decouple key name from path, and make 'parent' explicit.

Issue #2167109 by Berdir, sun, alexpott, ACF, acrollet, adamdicarlo, Albert Volkman, andreiashu, andyceo, andypost, anenkov, aspilicious, barbun, beejeebus, boombatower, cam8001, chriscalip, chx, cosmicdreams, dagmar, damiankloip, dawehner, deviance, disasm, dixon_, dstol, ebrowet, Gábor Hojtsy, heyrocker, Hydra, ianthomas_uk, japicoder, jcisio, jibran, julien, justafish, jvns, KarenS, kbasarab, kim.pepper, larowlan, Lars Toomre, leschekfm, Letharion, LinL, lirantal, Lukas von Blarer, marcingy, Mike Wacker, mrf, mtift, mtunay, n3or, nadavoid, nick_schuch, Niklas Fiekas, ParisLiakos, pcambra, penyaskito, pfrenssen, plopesc, Pol, Rok Žlender, rvilar, swentel, tim.plunkett, tobiasb, tsvenson, typhonius, vasi1186, vijaycs85, wamilton, webchick, webflo, wizonesolutions, xjm, yched, YesCT, znerol: Remove Variable subsystem.

This reverts commit f2769f4d.

Issue #2164367 by alexpott, tim.plunkett, dawehner: Rebuild router as few times as possible per request.