Unable to open new private tab by using keyboard shortcut while writing in a markdown box on Github

[Shnkc]

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

• Describe the issue you encountered:
  On github, while I am writing in a markdown box, if I try to open a new private tab by hitting cmd+shift+p, the markdown turns to preview mode.

• Platform (Win7, 8, 10? macOS? Linux distro?):
  MacOsX Sierra 10.12

• Brave Version (revision SHA):
  0.14.1 - 3de60d5

• Steps to reproduce:

  1. I write in a markdown box on Github (e.g. the markdown box of new issue page)
  2. I hit cmd+shift+p

• Actual result:
  The markdown box turns to preview mode

• Expected result:
  Brave opens a new private tab

• 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?
  Yes.

• Can this issue be consistently reproduced?
  Yes.

• Screenshot if needed:

• Any related issues:
  Unable to open private tab using keyboard shortcut from a PDF tab #4024

#2219

[cndouglas]

Related: #1867

A workaround is to unfocus the text field before pressing Cmd+Shift+P.

[luixxiul]

duping to #1867