Issue #3027653 by clayfreeman, tim.plunkett, Pavel Ruban, raman.b, ankithashetty, cboyden, larowlan, mpotter, phenaproxima: Allow block and layout plugins to determine if they are being previewed

Issue #3160629 by raman.b, tim.plunkett, Berdir: BlockPluginTrait cannot call ::addContextAssignmentElement() itself

Issue #2273381 by clayfreeman, tim.plunkett, andypost, dawehner, EclipseGc, jungle, xjm, alexpott, Berdir: Convert ContextAwarePluginBase to traits

Issue #3091309 by tim.plunkett, godotislate, paulocs, thursday_bw, alexpott, TwiiK: Broken context-aware block plugins throw an unexpected exception

Revert "Issue #2852463 by mikelutz, tim.plunkett, heddn, xjm, MegaChriz, joachim, phenaproxima, dawehner, benjifisher: Create a trait to implement \Drupal\Component\Plugin\ConfigurableInterface"

This reverts commit 109dfd58.

Issue #2852463 by mikelutz, tim.plunkett, heddn, xjm, MegaChriz, joachim, phenaproxima, dawehner, benjifisher: Create a trait to implement \Drupal\Component\Plugin\ConfigurableInterface

Issue #2959493 by bnjmnm, phenaproxima, tim.plunkett, tedbow, Adrian83, lauriii, xjm, andrewmacpherson, johndevman, KarenS, alwaysworking, jrockowitz, ckrina, cboyden, webchick, seanB, benjifisher, larowlan: Allow Layout Builder live previews to be toggled to allow easier drag-and-drop

(cherry picked from commit d028385c)

Issue #2992410 by tim.plunkett, scottsawyer, sugaroverflow, phenaproxima: Provide placeholders for empty blocks (for example, an empty Views listing)

Issue #2849669 by alexpott, pwolanin, Munavijayalakshmi, dawehner: Fix \Drupal\Component\Utility\Unicode() because of the Symfony mbstring polyfill

Issue #2935255 by Jo Fitzgerald, kim.pepper, voleger, alexpott, martin107, jibran, catch: Remove all usages of drupal_get_message and drupal_set_message in core lib

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 #2796953 by Wim Leers, mondrake, effulgentsia, catch, mikeryan, ayalon, chx, Fabianx, tim.plunkett, jibran, xjm, slashrsm, phenaproxima, borisson_: [regression] Plugins extending from classes of uninstalled modules lead to fatal error

Revert "Issue #2685917 by larowlan, tim.plunkett, cheeky-micah: Placing the same custom block, more than once, with a period in the title, results in an Error"

This reverts commit 803a98af.

Issue #2685917 by larowlan, tim.plunkett, cheeky-micah: Placing the same custom block, more than once, with a period in the title, results in an Error

Issue #2763157 by tim.plunkett, tedbow, chx, bojanz, twistor, neclimdul, dawehner, Xano, EclipseGc: Allow plugins to provide multiple forms

Revert "Issue #2773197 by jalpesh, tstoeckler: DefaultHtmlRouteProviderTest::testGetCollectionRoute() has wrong @covers"

This reverts commit a470bc0c.

Issue #2773197 by jalpesh, tstoeckler: DefaultHtmlRouteProviderTest::testGetCollectionRoute() has wrong @covers

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

Issue #2576533 by alexpott, stefan.r, Wim Leers, dawehner, xjm, effulgentsia, catch: Rename SafeStringInterface to MarkupInterface and move related classes

Issue #2377757 by EclipseGc, tim.plunkett, Frando, Berdir, japerry, dsnopek, Wim Leers, Bojhan: Expose Block Context mapping in the UI

Issue #2569069 by stefan.r, mr.baileys, alexpott, lauriii: Replace TranslationWrapper with TranslatableString and deprecate TranslationWrapper

Issue #2559605 by Cottser, stefan.r: Convert SafeMarkup::checkPlain() in render arrays to #plain_text

Issue #2375695 by Berdir, EclipseGc, tim.plunkett, Wim Leers, Fabianx, dawehner: Condition plugins should provide cache contexts AND cacheability metadata needs to be exposed

Issue #2508735 by darol100, dawehner, pwolanin, Chi, Fabianx, tim.plunkett: Code injection via preg_replace()

Issue #2375689 by Arla, Wim Leers, dawehner, tim.plunkett, Berdir: BlockBase::blockAccess() should return AccessResult instead of a bool

Issue #2459819 by Wim Leers, rteijeiro: Remove CacheableInterface (and no longer let block plugins implement it)

Issue #2444231 by Wim Leers, nlisgo: Fix CacheableInterface so it makes sense (was: "Make Config objects & Entities implement CacheableInterface + add BubbleableMetadata::createFromCacheableObject()")

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

Issue #2432837 by Wim Leers, Fabianx: Make cache contexts hierarchical (e.g. 'user' is more specific than 'user.roles')

Issue #2446995 by tim.plunkett, Berdir: Block content titles are not escaped on new block form (Port SA-CONTRIB-2013-082)

Issue #2329101 by Wim Leers: CacheableInterface only has a getCacheKeys() method, no getCacheContexts(), leads to awkward implementations

Issue #2318437 by Wim Leers, Gábor Hojtsy, geertvd: Replace the hardcoded langcode key on blocks with the 'language' cache context