Issue #2937853 by idebr, mfernea, SherFengChong, alexpott, borisson_: Fix 'Drupal.Formatting.MultipleStatementAlignment' coding standard

(cherry picked from commit 6c40e077)

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 #2515018 by joshi.rohit100, sdstyles, joelpittet: Lowercase the instances of camelcase'd instanceOf in core for consistency

Issue #2568613 by alexpott, lauriii, pwolanin: Remove HTML support from date formats and replace remaining !placeholder where format_date() and 'date.formatter' => format() are used

Issue #1835016 by googletorp, nod_, KarenS, Sharique, Nitesh Sethia, mpdonadio: Polyfill date input type

Issue #1493324 by tim.plunkett, dmsmidt, mgifford, bleen18, davidhernandez, crasx, mparker17, stefan.r, YesCT, joelpittet, tstoeckler, larowlan, vijaycs85, swentel, rpayanm, Bojhan, LewisNyman, emma.maria, BarisW, njbarrett, rteijeiro, nod_, sun, joshtaylor, mrjmd, webchick, marcvangend, kattekrab, SKAUGHT, bowersox, andrewmacpherson, Manjit.Singh, RavindraSingh, Wim Leers, BLadwin, aspilicious, mortendk, mausolos, jessebeach, Gábor Hojtsy, anandps, falcon03, franz, andypost, rooby, rootwork, Cottser, Xano: Inline form errors for accessibility and UX

Issue #2335659 by tim.plunkett, dawehner, effulgentsia, sun: Remove FormState ArrayAccess usage from core.