Fix bug affecting width of tabs when closing them with the mouse

[petemill]

Fix #11434

The tabs are meant to stay the same size until mouseout, according to #6088 and implemented in #6342. They were sometimes growing (or shrinking) on click and then shrinking further on mouseout due to the size being calculated at the wrong time.

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.

Test Plan (manual):

flex tabs

• Make the window narrow
• Open ~7 tabs (enough for the tabs to fill the width of the container and get smaller)
• Mouse over the first tab's close button and click it
• Expected: The next tab stays exactly the same size, and the next tab's close button is directly under the mouse, until mouseout of the tab bar

max-width tabs

• Make the window wider
• Open ~3 tabs (not enough for the tabs to fill the width of the container and get smaller)
• Mouse over the first tab's close button and click it
• Expected: The next tab stays exactly the same size, and the next tab's close button is directly under the mouse, until mouseout of the tab bar

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 #11436 into master will decrease coverage by 0.01%.
The diff coverage is 0%.

@@            Coverage Diff             @@
##           master   #11436      +/-   ##
==========================================
- Coverage   52.46%   52.44%   -0.02%     
==========================================
  Files         268      268              
  Lines       25195    25182      -13     
  Branches     4021     4020       -1     
==========================================
- Hits        13218    13207      -11     
+ Misses      11977    11975       -2

Flag	Coverage Δ
#unittest	52.44% <0%> (-0.02%)	⬇️

Impacted Files	Coverage Δ
...p/renderer/components/tabs/content/closeTabIcon.js	45.09% <0%> (+6.03%)	⬆️
js/stores/appStoreRenderer.js	91.17% <0%> (-8.83%)	⬇️
app/renderer/components/reduxComponent.js	84.37% <0%> (-6.25%)	⬇️
js/stores/windowStore.js	27.27% <0%> (-0.31%)	⬇️

[cezaraugusto]

+++++ works flawlessly, thanks!

[luixxiul]

Added to 0.22.x.

[petemill]

This PR also fixes #12837 which is assigned to 0.20, so changing milestone for this to 0.20 and uplifting to 0.21 and 0.20

[petemill]

0.21 57ff8d3
0.20 ffe02fe