Version 52.0beta, first offered to Beta channel users on January 25, 2017
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.
Enabled multi-process Firefox for 32-bit Windows users with touch screens
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.
Improved text input for third-party keyboard layouts on Windows. This will address some keyboard layouts that
have chained dead keys
input two or more characters with a non-printable key or a dead key sequence
input a character even when a dead key sequence failed to compose a character
Removed support for Netscape Plugin API (NPAPI) plugins other than Flash. Silverlight, Java, Acrobat and the like are no longer supported.
Removed Battery Status API to reduce fingerprinting of users by trackers
Improved experience for downloads:
Notification in the toolbar when a download fails
Quick access to five most recent downloads rather than three
Larger buttons for canceling and restarting downloads