Issue #2203435 by sun: Move all external libraries from core modules into core.libraries.yml.
Issue #2187717 by sun, dawehner: Remove code duplication in system_list() and ThemeHandler::rebuildThemeData().
Issue #2191011 by Stuart Miller, Cottser: PHP Warnings in views_preprocess_page() caused by frontpage view.
Issue #2209071 by tstoeckler: StringItem should cast the 'length' schema value to (int).