Issue #2579847 by marcvangend, hussainweb, YesCT, dawehner, chx, Wim Leers:...

Issue #2579847 by marcvangend, hussainweb, YesCT, dawehner, chx, Wim Leers: /node/add is lacking cacheability metadata, causes problems when cached by Dynamic Page Cache and "Use admin theme when editing or creating content" is turned off