fix(frequencies): sort trips with frequencies by Frequency#startTime …

…values

fixes #191

lib/editor/util/index.js

@@ -54,6 +54,12 @@ export function sortAndFilterTrips (
       // Sort by first arrival time. If they are the same, fall back on first
       // departure time. Finally, sort by trip ID.
       .sort((a, b) => {
+        if (a.frequencies.length > 0 && b.frequencies.length > 0) {
+          // Sort frequency trips purely by start time. (Stop times are all
+          // the same for frequencies of the same pattern.) Generally, a trip
+          // only has one frequency entry (for now).
+          return a.frequencies[0].startTime - b.frequencies[0].startTime
+        }
         // There may be a case where a null value (skipped stop) appears first
         // in the list of stopTimes. In this case, we want to compare on the
         // first stopTime that exists for each pair of trips.