View source not working in Firefox beta 39.0b7

[acrobat1]

In Firefox beta 39.0b7 the view source context (right-click) option doesn't work, it now prompts directly for script installation instead of opening the code in a tab: for instance, on this page https://greasyfork.org/en/scripts/3840-translate-on-google right-click the Install this script button, then click View User Script Source.
The gm-temp folder is created containing the actual script, but it doesn't get displayed in the browser even when dragging the script it in a tab.

[janekptacijarabaci]

Confirmed on:
Firefox 39.0 beta 1-7
Firefox Aurora 40.0a2 (2015-06-19) [e10s on/off]
Firefox Nightly 41.0a1 (2015-06-20) [e10s on/off]

Not confirmed on:
Firefox 38.0.5

And apparently it's the similar bug as #2178

[yfdyh000]

Hi @arantius, the seems is not works for the "View User Script Source" menu.

[arantius]

Does 3.4beta2 fix this?

https://addons.mozilla.org/firefox/downloads/file/341782/greasemonkey-3.4beta2-fx.xpi?src=devhub

[yfdyh000]

Looks works fine for Fx40~43, but the seems breaking for 35.0.1 (our min are 35.0).

[arantius]

Launched Firefox 35.0.1, view source works from both context menu and install dialog. Breaking how?