Managed to reproduce the issue one time with 72.0a1 (2019-11-07), 66.0b2; after that it was harder to reproduce.
Trying to get mozregression for the bisection was out of the question since the results where inconsistent for some reason.
While trying to get the regression range 59.0b14, 60.0.1.esr, 60.0b3 appear not having the options at all.
One thing worth mentioning is that steps 1+2 are really important:
- Uncheck "Restore previous session" in Firefox Options (Tools -> Options on Win, Firefox -> Preferences on OSX)
- the Restart afterwards.
In some cases the restart was not needed as the issue manifested but it persisted until the above mentioned steps were re-run.
Inclined to say it's not a regression in the end, but something that came up @60; if indeed it's the version this feature was added.
Versions before didn't have the context menu options at all.
Anyone who could confirm this?