For Desktop port of `request_open_auxiliary_webview`, stay on the
original WebView if the request originates WebDriver.
This is to make sure `webdriver_server::handle_new_window` does not
focus the new window, according to spec. See
c7eba2dbba/tests/wpt/tests/webdriver/tests/classic/new_window/new_window.py (L31-L37)
**To clarify**: this won't change the behaviour when user interacts, but
only affects WebDriver [New
Window](https://w3c.github.io/webdriver/#new-window).
Testing: `./mach test-wpt -r --log-raw "D:/servo log/all.txt"
./tests/wpt/tests/webdriver/tests/classic --product servodriver` based
on 96b0973037
---------
Signed-off-by: Euclid Ye <yezhizhenjiakang@gmail.com>
a3c792e5aa