Comment 4 for bug 1504501

Closing, it is intentional and not a regression:
https://trello.com/c/gqwsJcsa/2237-273-ubuntu-landing-014-webbrowser-app-osomon

"This is expected: this silo removes the text selection mechanism that was broken beyond repair.
This is not really a regression as the functionality worked poorly and was unreliable. This will be re-implemented shortly and properly in oxide (https://launchpad.net/bugs/1376268)."