Issue #2560641 by alexpott, lauriii, Xano, borisson_, ianthomas_uk, olli: Remove all usages SafeMarkup::checkPlain() from render arrays

Revert "Issue #2560641 by alexpott, lauriii, Xano, borisson_, ianthomas_uk: Remove all usages SafeMarkup::checkPlain() from render arrays"

This reverts commit 31007609.

Issue #2560641 by alexpott, lauriii, Xano, borisson_, ianthomas_uk: Remove all usages SafeMarkup::checkPlain() from render arrays

Issue #2551511 by alexpott, stefan.r, RavindraSingh, pjonckiere, JeroenT, Mariano: Remove SafeMarkup::set() from AllowedTagsXssTrait

Issue #2535302 by mbaynton, Berdir, kgoel, claudiu.cristea, tim.plunkett, RavindraSingh, cilefen, dawehner: Selecting too many files with JS off causes WSOD with data loss

Issue #2321969 by rpayanm, subhojit777, prics, LinL, JeroenT, Temoor, prashantgoel, Mile23, pcambra, Sumi: Replace all instances of file_load(), file_load_multiple(), entity_load('file') and entity_load_multiple('file') with static method calls

Issue #2511472 by Wim Leers, Fabianx, dawehner: Refactor all usages of drupal_render()/Renderer::render() that break #2450993

Issue #2500527 by dawehner, tim.plunkett, effulgentsia: Rewrite \Drupal\file\Controller\FileWidgetAjaxController::upload() to not rely on form cache

Issue #2226621 by JeroenT, ianthomas_uk, lokapujya, pjonckiere, marcingy, LinL, Xano, rpayanm, piyuesh23: Remove usage of element_info(), element_child() and element_children(). Deprecate element_info_property()

Issue #2457887 by prateekMehta, stefan.r, rpayanm, alexpott: Use Utility\SafeMarkup class instead of Utility\String for placeholder(), checkPlain(),format() functions

Issue #2164601 by yched, jibran, amateescu, pfrenssen: Stop auto-creating FieldItems on mere reading of $entity->field[N]

Issue #2362227 by dawehner, mpdonadio, znerol, tim.plunkett, skipyT: Replace all instances of current_path()

Issue #2199637 by Berdir, sun, swentel: Replace "required" flag of Field module with proper dependencies.

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

Issue #2287727 by yched, swentel, alexpott: Rename Field[instance]Config classes and entity types (again).

Issue #2143291 by plach, alexpott, xjm, effulgentsia, pwolanin, swentel | yched: Clarify handling of field translatability.

Issue #2089331 by grom358 | thedavidmeister: [meta] Replace calls to check_plain() with Drupal\Component\Utility\String::checkPlain().

Issue #2136197 by andypost, jessebeach, swentel, longwave, Berdir: Move field/instance/widget/formatter settings out of annotation / plugin definition.

Issue #2072995 by claudiu.cristea, yched: Change notice: Move FAPI callbacks for file/image widgets in classes.

Issue #2050113 by swentel, longwave, Hydra, yched, marthinal, netsensei: PHP notice on multiple items image field.

Issue #2097691 by plopesc, amateescu: Move FIELD_CARDINALITY_UNLIMITED constant to FieldDefinitionInterface.

Issue #2050835 by Berdir | yched: Move Widget, Formatter, and FieldType plugin types to the Core\Field system.

Issue #2051923 by Berdir, dixon_, plach: Rename \Drupal\Core\Entity\Field\Field, related subclasses and interfaces to *FieldItemList.