@calamity: The named slot was added at [1], as a replacement to

<content select=".dropdown-item,hr" ...></content>

Are you sure that fully removing the named slot, will not result in unwanted content appearing within the action menu? 

[1] https://chromium-review.googlesource.com/c/chromium/src/+/898403/3/ui/webui/resources/cr_elements/cr_action_menu/cr_action_menu.html

The following revision refers to this bug:
  https://chromium.googlesource.com/chromium/src.git/+/6ae5f8de98d45794220de278e7313de5b181368a

commit 6ae5f8de98d45794220de278e7313de5b181368a
Author: Christopher Lam <calamity@chromium.org>
Date: Mon Dec 10 11:03:56 2018

[cr-action-menu] Use default slot.

This CL changes the API of cr-action-menu to use the entire light dom
supplied by the client. This was changed as part of the Polymer 2
upgrade to use a named slot, but since the action menu has no sections,
it may as well use the entire client light dom.

This CL fixes an issue where menu separators in the Bookmark Manager
were not being pulled into the cr-action-menu because they didn't
specify slot="item".

Bug:  906507 
Change-Id: I43e4380370d810c3f12228d83072027a282ff8d6
Reviewed-on: https://chromium-review.googlesource.com/c/1341731
Commit-Queue: calamity <calamity@chromium.org>
Reviewed-by: Demetrios Papadopoulos <dpapad@chromium.org>
Reviewed-by: Alan Cutter <alancutter@chromium.org>
Cr-Commit-Position: refs/heads/master@{#615081}
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