Revert "No Temasys alert on mobile Web"

This reverts commit b09e86352f.

css/unsupported-browser/_unsupported-mobile-browser.scss

@@ -67,16 +67,3 @@
         }
     }
 }
-
-// Temasys provide lib-jitsi-meet/modules/RTC/adapter.screenshare.js which
-// detects whether the browser supports WebRTC. If the browser does not support
-// WebRTC, it displays an alert in the form of a yellow bar at the top of the
-// page. The alert notifies the user that the browser does not support WebRTC
-// and, if Temasys provide a plugin for the browser, the alert contains a button
-// to initiate installing the browser. When Temasys do not provide a plugin for
-// the browser, we do not want the alert on the unsupported-browser page because
-// the notification about the lack of WebRTC support is the whole point of the
-// unsupported-browser page.
-iframe[name="adapterjs-alert"] {
-    display: none;
-}