Revert "ensure HistoryItem.time to be SMI"
Revert "ensure HistoryItem.time to be SMI"

This reverts commit c6abe20dcb850d95a160262787bab6248c775a12.

Note: .time is used (almost only) for float number division,
so not force it an integer.

gdh1995/vimium-plus,gdh1995/vimium-plus,gdh1995/vimium-plus