Issue #3266568 by mxr576, sourabhjain, quietone: Refactor array_merge() usage in loops as possible for performance

Issue #3164210 by jungle, sylus, Akhildev.cs, dww: Refactor array_merge() usage in loops as possible for performance

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 #1392754 by tss, justAChris, jhodgdon: Comply with new documentation standards for @file for namespaced class files

Issue #2335661 by Wim Leers, pwolanin, dawehner, Fabianx, larowlan, catch, Berdir: Outbound path & route processors must specify cacheability metadata

Issue #2213319 by sun, dawehner: Create a single Container CompilerPass to collect + add handlers to consumer service definitions.

Issue #1798296 by damiankloip, Xano, David_Rothstein, Crell, dawehner: Integrate CSRF link token directly into routing system.