MD History: Fix bottom shadow of synced device card when collapsed

Currently for synced device cards, the #history-item-container has a 2px bottom
border, .card-title has a 1px bottom border and the collapse section has no
borders. In this way, the overall synced device card will have a 2px border at
bottom when opened, but will result in a 3px bottom border when the collapse
section is closed, which is too thick.

This CL changed #history-item-container's bottom border to be 1px only and let
collapse section to have a 1px border, so that no matter the collapse section is
opened or closed, the overall synced device card will always have a 2px bottom


Cr-Commit-Position: refs/heads/master@{#407429}
1 file changed