firefox-47.0_1,1 - built-in PDF viewer does not work

[Anton Shterenlikht]

Since upgrading to firefox-47.0_1,1 via pkg on amd64 11-current laptop,
the built-in PDF plugin does not seem to work anymore.

I still have under Preferences -> Applications:

	PDF - Preview in Firefox.

Have I missed some change in the firefox setup?
Anybody else is seeing this?
Perhaps some other package is now needed to make this work?

Thanks

Anton