Issue #3415940 by longwave, kristiaanvandeneynde, Spokje: Convert CacheTagsInvalidator to use a service collector

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 #2776975 by joelpittet, dawehner, tim.plunkett, xjm, pfrenssen: March 3, 2017: Convert core to array syntax coding standards for Drupal 8.3.x RC phase

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

Issue #2454649 by Aki Tendo, dawehner: Cache Optimization and hardening -- [PP-1] Use assert() instead of exceptions in Cache::merge(Tags|Contexts)

Issue #2433595 by chx, Berdir: WebTestBase::refreshVariables only resets cache_tags.invalidator.checksum