UserAgent: Mozilla/5.0 (Macintosh; Intel Mac OS X 10.14; rv:63.0) Gecko/20100101 Firefox/63.0

Steps to reproduce the problem:
1. Have a really long list of items in a folder in the Bookmarks Bar.
2. Click the folder menu open
3. Notice that the "up arrow" element is present even though you're at the topmost menu item. 

What is the expected behavior?
In pre-Materials Chrome, Safari, FF, etc the "up arrow" menu item only shows up when you have dragged to the bottom of the list and activated menu scrolling.

What went wrong?
In post-Materials Chrome, both up and down arrow elements are visible in the menu at all times rather than as needed to indicate there are more items out of view at the top or bottom of the menu list.

Did this work before? No 

Chrome version: Version 72.0.3611.0 (Official Build) canary (64-bit)  Channel: n/a
OS Version: OS X 10.14
Flash Version: Shockwave Flash 31.0 r0

I am attaching screenshots of the behavior in the current Chrome Canary and in Safari for comparison.
 

Deleted: Screen Shot 2018-11-15 at 10.57.17 AM.png 338 KB

	Screen Shot 2018-11-15 at 10.57.17 AM.png 338 KB View Download

Deleted: Screen Shot 2018-11-16 at 8.05.18 AM.png 440 KB

	Screen Shot 2018-11-16 at 8.05.18 AM.png 440 KB View Download