Drop-down should match currently-entered time

Created by: fantasai

[Trying to note down the little things that trip me up in the new UI.]

Steps to Reproduce:

1. Start a new activity. The start time is pre-filled to right now.
2. Insert cursor on the time, edit. e.g. from 16:05 to 16:00
3. Try to pick something from the drop-down to auto-complete the activity.

Actual Results: Notice every choice for activity is based off 16:05 (original start time) instead of 16:00 (current value)

Expected Results: Auto-completes should be based off of 16:00 (edited start time, i.e. current value)