controllers/tabs/CurrentTourController.js: remove Chrome warning pop-up
controllers/tabs/CurrentTourController.js: remove Chrome warning pop-up

It pops up when playing tours in Firefox, which is quite distracting. And if
there are browser incompatibilities or other bugs, a pop-up warning is not the
best way to deal with them.

WorldWideTelescope/wwt-web-client,WorldWideTelescope/wwt-web-client