ensure no locale leaks from new Intl APIs
From #33534 (closed):
Firefox 76 enabled the following:
- numberingSystem and calendar options for the
Intl.NumberFormat
,Intl.DateTimeFormat
, andIntl.RelativeTimeFormat
constructors - the
Intl.ListFormat
API
Firefox 78 added support for Intl.DisplayNames
.
It looks like RelativeTimeFormat()
may leak the current locale if the caller passes undefined to the constructor instead of a locale string. Other APIs may have similar problems that could make it easier to perform fingerprinting based on the user's locale.
https://bugzilla.mozilla.org/show_bug.cgi?id=1625975
"Enable numberingSystem and calendar options by default"
https://bugzilla.mozilla.org/show_bug.cgi?id=1589095
"Add support for "type" and "style" options to Intl.ListFormat and enable Intl.ListFormat by default"
https://bugzilla.mozilla.org/show_bug.cgi?id=1557727
"Implement the Intl.DisplayNames proposal"