Revert "Issue #2570681 by juanse254, AndreaD, giancarlosotelo, lucastockmann, edurenye: when admin toolbar-oriented vertically a div is over the options"

This reverts commit 2acfed87.

Issue #2570681 by juanse254, AndreaD, giancarlosotelo, lucastockmann, edurenye: when admin toolbar-oriented vertically a div is over the options

Issue #2493475 by ifrik, walangitan, XaviP, jhodgdon, batigolix: Fix online docs references in Help to conform to our standards

Issue #2560783 by stefan.r, joelpittet, lauriii, Cottser, Sutharsan, kgoel, justAChris, Gábor Hojtsy, dawehner, jhodgdon, effulgentsia, xjm, andypost, googletorp: Replace !placeholder with :placeholder for URLs in hook_help() implementations

Issue #2569279 by dawehner, izus: Replace remaining !placeholder for Non-URL HTML outputs only in contextual.module

Issue #2559969 by alexpott: Make SafeStringInterface extend \JsonSerializable so we don't have to do so much string casting

Issue #2349819 by amateescu, swentel, Leksat, larowlan, dawehner, Gábor Hojtsy, mpdonadio, benjy, jmuzz, yched, jibran, marthinal, dmsmidt: String field type doesn't consider empty string as empty value

Issue #2078803 by Wim Leers, aspilicious, wmortada, Sumit kumar, mrjmd, John Cook: Change contextual links background color to match the styleguide

Issue #2338081 by pwolanin, dawehner, effulgentsia, kgoel, vijaycs85, mpdonadio, chx, brandon.holtsclaw, alexpott, Gábor Hojtsy, Fabianx, catch, YesCT, JvE: Local Tasks, Actions, and Contextual links mark strings from derivatives (or alter hooks) as safe and translated

Issue #2506581 by alexpott, Wim Leers, Fabianx, xjm, joelpittet, Cottser, dawehner: Remove SafeMarkup::set() from Renderer::doRender

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

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

Issue #2481453 by dawehner, pwolanin, rteijeiro, neclimdul, znerol: Implement query parameter based content negotiation as alternative to extensions

Issue #2273925 by larowlan, aneek, lauriii, mikey_p, joelpittet, dimaro, Fabianx, xjm, jaredsmith, effulgentsia, lokapujya, iMiksu, chx, YesCT, googletorp, dawehner, Wim Leers, Cottser: Ensure #markup is XSS escaped in Renderer::doRender()

Issue #2254865 by Wim Leers, lauriii, borisson_, JeroenT, alexpott, Fabianx: toolbar_pre_render() runs on every page and is responsible for ~15ms/17000 function calls

Issue #2491155 by mikeburrelljr, Mac_Weber, opdavies: Update drupal.org and kernel.org URLs in core modules (Follow-up to 2489912)

Issue #2473105 by ifrik, jhodgdon, lostkangaroo, opratr, LinL: Update hook_help texts that link to modules that can be uninstalled

Issue #2383865 by mgifford, pguillard, rpayanm, alexpott, jhodgdon: Spellchecking Drupal - Javascript

Issue #2031641 by aburrows, lauriii, nlisgo, Pol, redsquid, tuutti, LewisNyman, akalata, agviu, kallehauge, _nolocation, rpayanm, saki007ster, mdrummond, RavindraSingh, brahmjeet789: Change active class to is-active

Issue #2154475 by tarekdj, neelam.chaudhary, droplet, nod_, lanchez, Poornima3, jamin_melville: Convert position selectors to be compatible with with jQuery native-API selector

Issue #2448605 by martin107, willzyx, tim.plunkett, klausi, dpopdan: Replace usages of drupal_get_destination() with the redirect destination service

Issue #2457781 by prateekMehta, stefan.r, AjitS, hussainweb: Use Utility\Html class instead of Utility\String for decodeEntities() function

Issue #2404603 by mpdonadio, dawehner, larowlan, RavindraSingh: Add proper support for Url objects in FieldPluginBase::renderAsLink(), so we can remove EntityInterface::getSystemPath()

Broke testing UI. Reverted.

This reverts commit dc5ef576.

Issue #2382543 by rpayanm, ianthomas_uk: Remove usage of drupal_html_class() and drupal_clean_css_identifier()

Issue #2384165 by tibbsa: Clean-up Contextual module test members — ensure property definition and use of camelCase naming convention

Issue #2371457 by DuaelFr: Replace inappropriate translatatable string in core/modules/contextual/contextual.module.