LibJS: Add Temporal.Instant.compare()

Author: https://github.com/IdanHo
Commit: 33cf6274e8
Pull-request: https://github.com/SerenityOS/serenity/pull/8663
Reviewed-by: https://github.com/Hendiadyoin1
Reviewed-by: https://github.com/linusg

Userland/Libraries/LibJS/Runtime/Temporal/InstantConstructor.h

@@ -28,6 +28,7 @@ private:
     JS_DECLARE_NATIVE_FUNCTION(from_epoch_milliseconds);
     JS_DECLARE_NATIVE_FUNCTION(from_epoch_microseconds);
     JS_DECLARE_NATIVE_FUNCTION(from_epoch_nanoseconds);
+    JS_DECLARE_NATIVE_FUNCTION(compare);
 };
 
 }