Issue #2560729 by stefan.r, lauriii: Cast objects implementing SafeStringInterface to string in TestBase / WebTestBase

Issue #2555169 by TR: API documentation should not suggest using deprecated function format_string()

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 #2557519 by alexpott, joelpittet: Remove many usages SafeMarkup::checkPlain() and replace with Html::escape()

Issue #2501931 by alexpott, alimac, cmanalansan, davidhernandez, scotself, cilefen, RavindraSingh, peezy, YesCT, pwolanin: Remove SafeMarkup::set in twig_render_template() and ThemeManager and FieldPluginBase:advancedRender

Revert "Issue #2501931 by alexpott, alimac, cmanalansan, davidhernandez, scotself, cilefen, RavindraSingh, peezy, YesCT, pwolanin: Remove SafeMarkup::set in twig_render_template() and ThemeManager and FieldPluginBase:advancedRender"

This reverts commit 9ccb44e2.

Issue #2501931 by alexpott, alimac, cmanalansan, davidhernandez, scotself, cilefen, RavindraSingh, peezy, YesCT, pwolanin: Remove SafeMarkup::set in twig_render_template() and ThemeManager and FieldPluginBase:advancedRender

Issue #2546582 by alexpott, dawehner: AssertContentTrait::getTextContent() includes the @import css statement, that is nuts

Revert "Revert "Issue #2510104 by pwolanin, nod_, Fabianx, Wim Leers, droplet, Pere Orga: Convert drupalSettings from JavaScript to JSON, to allow for CSP in the future""

This reverts commit e8e883f9.

Revert "Issue #2510104 by pwolanin, nod_, Fabianx, Wim Leers, droplet, Pere Orga: Convert drupalSettings from JavaScript to JSON, to allow for CSP in the future"

This reverts commit 94615a13.

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

Issue #2510104 by pwolanin, nod_, Fabianx, Wim Leers, droplet, Pere Orga: Convert drupalSettings from JavaScript to JSON, to allow for CSP in the future

Issue #2450993 by Wim Leers, Fabianx, Crell, dawehner, effulgentsia: Rendered Cache Metadata created during the main controller request gets lost

Issue #1305882 by dawehner, nod_, Fabianx, Steven Jones, sun, nlisgo: drupal_html_id() considered harmful; remove ajax_html_ids to use GET (not POST) AJAX requests

Issue #2383871 by mgifford, rpayanm, a_thakur, maximpodorov, AohRveTPV, jhodgdon: Spellchecking Drupal - PHP

Issue #1882788 by jabberwooki, keopx, joshi.rohit100, jhodgdon: assertText/assertNoText doesn't really show what you could see in the browser (bad docs)

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

Issue #2342045 by dawehner, Gábor Hojtsy, larowlan, joshtaylor: Standard views base fields need to use same rendering as Field UI fields, for formatting, access checking, and translation consistency

Revert "Issue #2273923 by mpdonadio, pfrenssen, dawehner, xjm, cilefen: Remove html => TRUE option from l() and link generator"

This reverts commit 0bcabf50.

Issue #2273923 by mpdonadio, pfrenssen, dawehner, xjm, cilefen: Remove html => TRUE option from l() and link generator

Issue #2340785 by mpdonadio: Create proper test method for determining if text has been escaped properly.

Issue #2347465 by tim.plunkett, dawehner, cilefen: Convert all instances of #type link/links to convert to use routes.

Issue #2325571 by asif_khan, omers | dawehner: Replace _theme() calls by calls to \Drupal::theme()->render().

Issue #2257519 by sun, larowlan, xjm, cs_shadow: Move content assertion methods into a trait, so DUTB can consume it, too.