This is a reland of commit 95f912cedcfed49b1360d308897f441882b57f13

Original change's description:
> Refactor menu event handling code [2/4]
>
> Another refactoring CL for menu element code. Previously, the command
> invoker logic was split (and roughly duplicated) between
> HTMLButtonElement and HTMLMenuItemElement. Since both can be command
> invokers, it makes sense to move the command management stuff to the
> common ancestor class, HTMLElement. This CL does that, and de-dupes
> the code out of both subclasses. There is now just one base class
> method that is overridden in sub-classes that can be command
> invokers: CanBeCommandInvoker().
>
> There was also a weird combination of popover activation command
> code, which belongs on HTMLElement because any element can be a
> popover, and menu activation command code, which belongs on the
> HTMLMenuItemElement class, because only that class handles menu
> commands.
>
> This touches a few outside classes like ax_object, which get simpler
> now that they don't have to deal with each case of a command invoker.
>
> There is one behavior change here: now, if a menuitem is *both*
> checkable *and* a sub-menu invoker, the sub-menu wins, and the
> item does not do checked/unchecked behaviors.
>
> I also added a test that seemed missing: make sure only buttons and
> menuitems can be command invokers. Even though <menuitem> isn't
> shipped, this test should pass because it explicitly skips <menuitem>,
> and anyway menuitem isn't included in the HTML5_ELEMENTS list.
>
> Bug: 406566432
> Change-Id: I281eda0eda4b0dced3ad38bd09a488f2c6b1ddf4
> Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/7078858
> Reviewed-by: Dominic Farolino <dom@chromium.org>
> Commit-Queue: Mason Freed <masonf@chromium.org>
> Cr-Commit-Position: refs/heads/main@{#1538871}

Bug: 406566432
Change-Id: Iec91410726ae22a3673bdf32eb64aad79f672d6a
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/7113161
Commit-Queue: Dominic Farolino <dom@chromium.org>
Auto-Submit: Mason Freed <masonf@chromium.org>
Reviewed-by: Dominic Farolino <dom@chromium.org>
Cr-Commit-Position: refs/heads/main@{#1540144}