Esto me funciona con la última versión de Mac OS High Sierra.
tell application "Google Chrome"
tell its window 1
set theURL to URL of active tab
close active tab
end tell
set the URL of active tab of (make new window) to theURL
end tell
Si desea ver las dos ventanas ahora una al lado de la otra, intente esto ...
tell application "Finder"
set currentDesktopBounds to bounds of window of desktop
end tell
copy currentDesktopBounds to leftBounds
set l to item 3 of leftBounds
set l to l / 2 as integer
set item 3 of leftBounds to l
copy leftBounds to rightBounds
set r to item 3 of rightBounds as integer
set r to r + 1 as integer
set item 1 of rightBounds to r
set item 2 of rightBounds to 22
set item 3 of rightBounds to item 3 of currentDesktopBounds
set item 4 of rightBounds to item 4 of currentDesktopBounds
tell application "Google Chrome"
tell its window 1
set theURL to URL of active tab
close active tab
end tell
set the URL of active tab of (make new window) to theURL
delay 0.2
tell its window 1
set bounds to leftBounds
end tell
delay 0.2
tell its window 2
set bounds to rightBounds
end tell
end tell