Fixes dev tools inspect element functionality

[NejcZdovc]

Submitter Checklist:

• Submitted a ticket for my issue if one did not already exist.
• Used Github auto-closing keywords in the commit message.
• Added/updated tests for this change (for new code or code which already has tests).
• Ran git rebase -i to squash commits (if needed).
• Tagged reviewers and labelled the pull request as needed.

Resolves #10249

Auditors: @bridiver

Test Plan:

1. Open context menu
2. Click Inspect Element

Reviewer Checklist:

Tests

• Adequate test coverage exists to prevent regressions
• Tests should be independent and work correctly when run individually or as a suite ref
• New files have MPL2 license header

[codecov-io]

Codecov Report

Merging #10660 into master will decrease coverage by 0.01%.
The diff coverage is 0%.

@@            Coverage Diff             @@
##           master   #10660      +/-   ##
==========================================
- Coverage   54.54%   54.53%   -0.02%     
==========================================
  Files         245      245              
  Lines       21156    21160       +4     
  Branches     3263     3264       +1     
==========================================
  Hits        11539    11539              
- Misses       9617     9621       +4

Flag	Coverage Δ
#unittest	54.53% <0%> (-0.02%)	⬇️

Impacted Files	Coverage Δ
js/actions/webviewActions.js	10.63% <ø> (+1.37%)	⬆️
js/constants/appConstants.js	100% <ø> (ø)	⬆️
js/actions/appActions.js	12.76% <0%> (-0.1%)	⬇️
js/contextMenus.js	17.92% <0%> (ø)	⬆️
app/browser/reducers/tabsReducer.js	49.36% <0%> (-0.8%)	⬇️
app/browser/tabs.js	26.48% <0%> (-0.16%)	⬇️

[bridiver]

++