Issue #2232477 by tstoeckler, a 'fliptable' mateescu, plach: Fixed Fatal when adding new fields with NOT NULL constraints in a base table that contains existing entities.
Issue #2371725 by dawehner: Fixed Don't use theme negotiation all over the place.
Issue #2371671 by podarok | Chi: Fixed drupal_set_message repeat parameter does not work.
Issue #2371141 by pfrenssen: Fixed XSS vulnerability when displaying exception backtrace.
Issue #2364647 by chx, alexpott: Fixed [sechole] Remove blacklist mode from Filter:XSS.
Issue #2342377 by david_garcia: Fixed Non database agnostic expression in SQLContentEntityStorage.
Issue #2352155 by Wim Leers: Remove HtmlFragment/HtmlPage.
Revert "Issue #2232477 by tstoeckler, a 'fliptable' mateescu, plach: Fixed Fatal when adding new fields with NOT NULL constraints in a base table that contains existing entities."

This reverts commit 08d3ebba69520f2e800323709201d85c9c80527c.