Fixes upgrade of bookmark/folder width

[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.
• Request a security/privacy review as needed. (Ask a Brave employee to help if you cannot access this document.)

Resolves #9517
Resolves #9939

Auditors:

Test Plan:

• use existing profile from 0.19.x with bookmarks and folder on the toolbar
• start browser
• make sure that bookmarks are hidden accordingly when you resize the window

Reviewer Checklist:

• Request a security/privacy review as needed if one was not already requested.

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 #12768 into master will decrease coverage by 0.02%.
The diff coverage is 100%.

@@            Coverage Diff             @@
##           master   #12768      +/-   ##
==========================================
- Coverage   56.13%    56.1%   -0.03%     
==========================================
  Files         279      279              
  Lines       27309    27316       +7     
  Branches     4442     4443       +1     
==========================================
- Hits        15329    15327       -2     
- Misses      11980    11989       +9

Flag	Coverage Δ
#unittest	56.1% <100%> (-0.03%)	⬇️

Impacted Files	Coverage Δ
app/browser/reducers/bookmarkToolbarReducer.js	100% <100%> (ø)	⬆️
js/stores/appStoreRenderer.js	91.17% <0%> (-8.83%)	⬇️
app/renderer/components/reduxComponent.js	84.61% <0%> (-6.16%)	⬇️
js/stores/windowStore.js	27.25% <0%> (-0.31%)	⬇️

[bsclifton]

Having a problem with this one ☹️ When window is wider than ~1,138 pixels, it seems like the >> doesn't always show

[bsclifton]

See feedback

[bsclifton]

With your latest updates, this works great 😄 👍 Thanks for fixing the edge case

[bsclifton]

master 8d4531e
0.21.x bcd2de6
0.20.x 48dfb13