Affected versions:
Nightly 68.0a1 (2019-04-02) (64-bit)
Beta 67.0b7 (64-bit)
Release 66.0.2

Affected platform:
Windows 7/10
Ubuntu 16.04
Mac OS 10.13

Steps to reproduce:

• Launch Firefox
• Go to http://www23.statcan.gc.ca/imdb-bmdi/pub/instrument/3901_Q2_V3-eng.pdf
• Bookmark the pdf page
• Enter presentation mode (button on the left side of printing)
• Right click to open context menu
• Click on the Star button (Edit this bookmark)

Expected result:
Presentation mode should be exited to edit the bookmark or the edit button should not be available in the context menu

Actual Results:
Clicking on the Edit button does nothing. Browser console error can be seen in attached screenshot.

Regression-range: will try to find it asap.

Regression window:
https://hg.mozilla.org/mozilla-central/pushloghtml?fromchange=5f3f19824efa14cc6db546baf59c54a0fc15ddc9&tochange=641bfddb87113b45ee3df9849345dbcf821ef3da

Suspect:
86a27018d5bc Drew Willcoxon — Bug 1402721 - Add/edit bookmark panel should open anchored on the page action (ellipsis) button instead of on the identity block (left side of the address bar) when the bookmarks star action is not pinned/visible. r=Gijs

Thanks for the regression range Alice!

Reproduced on latest Nightly build 71.0a1 (2019-09-12) on Windows 7 x64.