Align browsers on user activation for extension API: allow `auxclick` and `contextmenu` DOM events

[tophf]

Chrome: mousedown, keydown, auxclick, contextmenu.
Firefox: mousedown, keydown.

[carlosjeurissen]

Did you test other events and on mobile as well? The HTML spec mentions pointerdown on desktop while on mobile, pointerdown is not enough and pointerup is required.

[tophf]

No, I don't have a mobile device for the time being.

[tophf]

pointerdown and pointerup keep activation in Firefox (and Chrome) on desktop - probably because they are internally similar to mousexxxx.

[tophf]

Looks like this is where Firefox limits the events: https://searchfox.org/firefox-main/source/dom/base/UserActivation.cpp#86