Removing the NaN timestamp error.

Instead a timestamp should appear when you click on the first block in the timeline.

This error occurred due to a negative index in the extreme case.

Bug: 15272217
Test: run a trace, click on the first block in the timeline, check the timestamp to ensure NaN does not appear.
Change-Id: Id829ee773ff68c2a911fbfc35adf0e228701a955
1 file changed