fix(TransitionablePortal): fix onClose call

[mterezac]

Fixes #4056.

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• Run yarn lint locally to catch formatting errors. This will fix some errors automatically, commit and push any changes.
• Run yarn test locally to catch errors. This ensures all components still behave as they should.
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• Include tests when adding/changing behavior.

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[codecov-commenter]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 99.75%. Comparing base (bb2db59) to head (1fe1aac).
⚠️ Report is 76 commits behind head on master.

Additional details and impacted files

@@           Coverage Diff           @@
##           master    #4334   +/-   ##
=======================================
  Coverage   99.75%   99.75%           
=======================================
  Files         180      180           
  Lines        3241     3243    +2     
=======================================
+ Hits         3233     3235    +2     
  Misses          8        8           

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