start-tor-browser.desktop parameter passing broken on spaces

Steps to reproduce:

  1. install Tor Browser to /home/user/.tb/tor-browser (but any folder should work if you adjust the paths below)
  2. Go to https://check.torproject.org
  3. Save that website under /home/user/Downloads/
  4. There now will be a file "/home/user/Downloads/Congratulations. This browser is configured to use Tor..html" (any other long file name with spaces should work also)

The following commands to work as expected:

bash -x /home/user/.tb/tor-browser/Browser/start-tor-browser --new-tab "/home/user/Downloads/Congratulations. This browser is configured to use Tor..html"
bash -x /home/user/.tb/tor-browser/Browser/start-tor-browser "/home/user/Downloads/Congratulations. This browser is configured to use Tor..html"
firefox "/home/user/Downloads/Congratulations. This browser is configured to use Tor..html"

The following fails:

/home/user/.tb/tor-browser/start-tor-browser.desktop "/home/user/Downloads/Congratulations. This browser is configured to use Tor..html"

Expected result: Open that file and show it in Tor Browser as the other above commands working for Firefox / Tor Browser should do.

Actual result: Tor Browser opens ~ 10 links that do not work. To Congratulations., This, etc.

Impact: This currently prevents Whonix users [Whonix is using Tor Browser by default] to open local html files.

Workaround: We could use Browser/start-tor-browser directly instead, which would work, if that is now the canonical way to do this.

But perhaps parameter passing can be fixed in start-tor-browser.desktop?

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