data delivery: Use right time-related variable in passes rate test check

Follow-up to #274, related to #257.

The call to the "passes rate test" algorithm should use `timeValue` rather
than `timestamp`: the former is what is stored in `PressureRecord.[[Time]]`,
so it makes sense to compare values that have been similarly coarsened and
converted to a relative time.

index.html

@@ -1159,7 +1159,7 @@ <h3>Data delivery</h3>
               returns false, [=iteration/continue=].
             </li>
             <li>
-              If running [=passes rate test=] with |observer|, |source| and |timestamp|
+              If running [=passes rate test=] with |observer|, |source| and |timeValue|
               returns false, [=iteration/continue=].
             </li>
             <li>