LibJS: Implement Temporal.TimeZone.prototype.getPreviousTransition()

Author: https://github.com/linusg
Commit: 92fdae178b
Pull-request: https://github.com/SerenityOS/serenity/pull/10700
Reviewed-by: https://github.com/IdanHo ✅

Userland/Libraries/LibJS/Runtime/Temporal/TimeZone.cpp

@@ -186,6 +186,15 @@ BigInt* get_iana_time_zone_next_transition(GlobalObject&, [[maybe_unused]] BigIn
     return nullptr;
 }
 
+// 11.6.7 GetIANATimeZonePreviousTransition ( epochNanoseconds, timeZoneIdentifier ), https://tc39.es/proposal-temporal/#sec-temporal-getianatimezoneprevioustransition
+BigInt* get_iana_time_zone_previous_transition(GlobalObject&, [[maybe_unused]] BigInt const& epoch_nanoseconds, [[maybe_unused]] StringView time_zone_identifier)
+{
+    // The abstract operation GetIANATimeZonePreviousTransition is an implementation-defined algorithm that returns an integer representing the number of nanoseconds since the Unix epoch in UTC that corresponds to the last time zone transition before epochNanoseconds in the IANA time zone identified by timeZoneIdentifier or null if no such transition exists.
+
+    // TODO: Implement this
+    return nullptr;
+}
+
 // https://tc39.es/proposal-temporal/#prod-TimeZoneNumericUTCOffset
 static bool parse_time_zone_numeric_utc_offset_syntax(String const& offset_string, StringView& sign, StringView& hours, Optional<StringView>& minutes, Optional<StringView>& seconds, Optional<StringView>& fraction)
 {