Regression: Can't use CiviCRM menu on 5.16.0

I've had a number of my clients report this to me, and I can replicate it on their sites, but not master. I suspect there's a race condition involved - especially because clearing caches causes this problem to fix itself once, but not a second time.

Without this bug, this is the <ul> element that surrounds all the CiviCRM menu items: <ul id="civicrm-menu" class="sm sm-civicrm" data-smartmenus-id="15656273348750613">

With this bug it's: <ul id="civicrm-menu" class="sm sm-civicrm">

This commit is the issue. When I roll back to the version of the file from before this commit, I don't experience the problem. With this commit, I do. I note that there's only one HTML element with an id of crm-container but several with the class of crm-container. I imagine that under certain circumstances one of those elements loads before the menubar, causing crm.menubar.js to not work.