tell application "Safari"
    repeat with site in sitelist
        repeat with w from 1 to number of windows
            set tabList to (every tab of window w whose URL contains site)
        end repeat
    end repeat
end tell
tell application "Chrome"
    repeat with site in sitelist
        repeat with w from 1 to number of windows
            set tabList to (every tab of window w whose URL contains site)
        end repeat
    end repeat
end tell

set browserlist to {"Safari", "Chrome"}

repeat with browser in browserlist
    tell application browser
        repeat with site in sitelist
            repeat with w from 1 to number of windows
                set tabList to (every tab of window w whose URL contains site)
            end repeat
        end repeat
    end tell
end repeat

set tabList to (every tab of window w whose URL contains site)