Chrome Version: 68
OS: Chrome

What steps will reproduce the problem?
Turn on chrome://flags#secondary-ui-md
(1) Install a bookmark app (e.g., https://permission.site).
(2) Open permission prompt (click any of the permission buttons).

What is the expected result?
Permission prompt should highlight the 3-dot menu. (Due to no longer having an arrow.)

What happens instead?
Permission prompt has no arrow, but also doesn't highlight the 3-dot menu.

This should not change the behaviour without the #secondary-ui-md flag.