Version 52.0, first offered to Release channel users on March 7, 2017
We'd also like to extend a special thank you to all of the new Mozillians who contributed to this release of Firefox!
Added support for WebAssembly, an emerging standard that brings near-native performance to Web-based games, apps, and software libraries without the use of plugins.
Added automatic captive portal detection, for easier access to Wi-Fi hotspots. When accessing the Internet via a captive portal, Firefox will alert users and open the portal login page in a new tab.
Enhanced Sync to allow users to send and open tabs from one device to another.
Added user warnings for non-secure HTTP pages with logins. Firefox now displays a “This connection is not secure” message when users click into the username and password fields on pages that don’t use HTTPS.
Implemented the Strict Secure Cookies specification which forbids insecure HTTP sites from setting cookies with the "secure" attribute. In some cases, this will prevent an insecure site from setting a cookie with the same name as an existing "secure" cookie from the same base domain.