Setting new window or simply open the link may be done in the code, but the choice of new tab or new window is done in the browser.
They are two separate issues, don't confuse them.
You can dictate within the browser settings how to handle new windows (tab or new window), so yes, the browser does decide.
For example, firefox supports tabs but I can disable it so all links such as that you posted above will open in a new window.
There is no code that can force a tab unless the browser is already set to do so.