   assert_true(eventName in eventsWithFractions,
                                        eventName + " should have fractional coordinates");
                                }
                            });
                            // At this point, we know that `eventsWithFractions` contains all
                            // of `eventList` except "click".  The assert below rules out any
                            // extra entry in `eventsWithFractions`.
                            assert_equals(Object