Answer-time tests check the answer, not wall-clock milliseconds (closes #316)

The waf test that asks a question while every outside source hangs now
runs it in a synctest bubble and checks that the answer comes after
exactly the GeoJS wait, within the time limit. GeoJS is the silent
stand-in; the lists are fetched outside the bubble. The routewatch test
for a hanging routewatch checks that Route answers no_answer_yet instead
of timing it.

Model: opus-5-5

internal/routewatch/routewatch_test.go

@@ -291,12 +291,11 @@ func TestHangingRoutewatchNeverDelaysAndFailsTheQuery(t *testing.T) {
 		<-r.Context().Done()
 	})
 
-	start := time.Now()
-
-	f.route()
-
-	if elapsed := time.Since(start); elapsed > time.Second {
-		t.Errorf("Route took %s while routewatch hangs", elapsed)
+	// Route answers no_answer_yet while the query is under way, and
+	// request_failed once it has failed, after queryTimeout.
+	if _, missing := f.route(); missing != routewatch.NoAnswerYet {
+		t.Errorf("Route gave %q while routewatch hangs, want %q",
+			missing, routewatch.NoAnswerYet)
 	}
 
 	f.waitFor(routewatch.RequestFailed)