Funziona per me usando l'ultima versione di 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
Se desideri vedere le due finestre ora affiancate, prova questo ...
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