UserAgent: Mozilla/5.0 (X11; CrOS x86_64 10895.40.0) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/69.0.3497.73 Safari/537.36
Platform: 10895.40.0 (Official Build) beta-channel samus

Steps to reproduce the problem:
1. Receive multiple notifications
2. Open Notifications area
3. Dismiss notifications, starting from the bottom

What is the expected behavior?
Notifications will shift down as the Notification area resizes to fit the new total number of notifications (or a maximum area).

What went wrong?
Notification area remains original size and remain in place.

Did this work before? N/A 

Chrome version: 69.0.3497.73  Channel: n/a
OS Version: 10895.40.0
Flash Version: 30.0.0.154 /opt/google/chrome/pepper/libpepflashplayer.so

Dismissing notifications towards the top of the list _does_ shift notifications upwards.  

The upwards notification dismissal feels more natural on mobile where the notification area is located at the top of the user interface.  Where the notification area is at the bottom (even when the shelf is placed on the sides) a downward movement makes more sense, even though different sized notification may move the location of the Close/Dismiss 'X'.  With Swipe dismissal, this makes the location of the 'X' less of an issue.