Failed to calculate CSS selector for inspected elements

[Bacia-Mociran Vlad-Ionut]

[Affected versions]:

• Firefox Nightly 67.0a1
• FathomFox 2.3.1

[Affected Platforms]:

• Windows 10

[Prerequisites]:

• Latest FathomFox add-on is installed
• Link with issues:
  • https://secure05b.chase.com/web/auth/dashboard#/dashboard/index/index

[Steps to reproduce]:

1. Open the above link into Firefox.
2. Right-click on the Username field and Inspect Element.
3. Inspected element is selected.
4. Reach the Fathom tab from DevTools.
5. Observe the element selected in Fathom tab.

[Expected results]:

• The selected element is displayed and can be labeled.

[Actual results]:

• A message is displayed: " Failed to calculate CSS selector"

[Notes]:

• Screen recorder of the issue attached:

[Erik Rose]

This looks like a repeat of mozilla/fathom-fox#15. I guess we'll have to crank up the max depth even further.

[Bacia-Mociran Vlad-Ionut]

Also, this issue is happening for: https://www.miniclip.com/games/en/# -> Click on "Signup / Login" button -> Login popup is displayed -> Inspect Email field -> open Fathom from DevTools

[Bacia-Mociran Vlad-Ionut]

This issue has been verified on Nightly Build ID: 20190331215222 with FathomFox 3.0 and it is reproducible.