Is there a way to enable Firefox loading WebExtension Experimental extension after Firefox 57?

Hi Genius,

As we known all the legacy extension will be stopped supported after Firefox 57. My question is there a way to enable load the WebExtension Experimental extension after Firefox 57 in developer edition, nightly or customized build Firefox?
This request is due the current implementation of the WebExtension API are not fully equal to Chrome API. We have a project which required to use WebExtension Experimental extension fill in the gap betweens these APIs.

Thanks in advance!

Yes… I am running some legacy addons in Firefox 57.0a1 Nightly.

about:config -> extensions.legacy.enabled -> true

Wow! Thank you so much @erosman!!!