Fix missing ending from engineering english text
[sailfish-browser] Enable chrome when active tab is changed. Contributes to JB#17255
Add qDebug support for Tab class
Fix closing of active tab
Improve tab data update guards
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.
Cleanup active thumbnail handling
Cleanup unused property