Left-arrow navigation to flow events displays no event data in canary

[randomascii]

On canary builds of Chrome on Windows (including 43.0.2321.0, but the problem started before then) if you select a RunTask event and then type left-arrow you go to the 'finish' node of the associated flow event (the previous "f" event on the same thread) no data is displayed. You have to press left again (to go to the associated "s" event) and then press right in order to see the data.

This is very confusing, especially for new users.

This works correctly on stable (on Windows).

Expected:

Selected Flow Event:
Title: "MessageLoop::PostTask"
Category "disabled-by-default-toplevel.flow"
Start 9253.923 ms
Wall Duration 0 ms
Args
queue_duration 649

Actual:

Flow Event

[randomascii]

Screenshots -- from stable:

and from canary (same trace, same flow event):

[catapult-bot]

Migrated to catapult-project/catapult#786