Multi-day events should be correctly calculated for new js layout

Summary: Fixes T8304, Multi-day events should be correctly calculated for new js layout

Test Plan: A day with events starting before midnight of the displayed day should be correctly placed and fitted for day view.

Reviewers: epriestley, #blessed_reviewers

Reviewed By: epriestley, #blessed_reviewers

Subscribers: Korvin, epriestley

Maniphest Tasks: T8304

Differential Revision: https://secure.phabricator.com/D13008