Window is closed after a tear off

[NejcZdovc]

Test plan

1. open two tabs
2. tear off one tab into new window
3. window 1 should remain

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• Did you search for similar issues before submitting this one?
  yes

• Describe the issue you encountered:
  If you tear off a tab from a window that have only two tabs, window is closed.

• Platform (Win7, 8, 10? macOS? Linux distro?):
  macOS

• Brave Version (revision SHA):
  26afbd5

• Steps to reproduce:

  1. open two tabs
  2. tear off one tab into new window

• Actual result:
  window 1 is closed

• Expected result:
  window 1 should remain

• Will the steps above reproduce in a fresh profile? If not what other info can be added?
  yes

• Is this an issue in the currently released version?
  no

• Can this issue be consistently reproduced?
  yes

• Screenshot if needed:
  

[alexwykoff]

Fixed by #8863