Fix back / forward navigation error to not trigger load when not needed
Fix back / forward navigation error to not trigger load when not needed

DeclarativeWebContainer should only trigger load due to back / forward
navigation when QuickMozView instance cannot be used.

sailfishos/sailfish-browser,alinelena/sailfish-browser,sailfishos/sailfish-browser,sailfishos/sailfish-browser,alinelena/sailfish-browser,alinelena/sailfish-browser,sailfishos/sailfish-browser,alinelena/sailfish-browser,rojkov/sailfish-browser,rojkov/sailfish-browser,sailfishos/sailfish-browser,rojkov/sailfish-browser