You can't search for URLs via the top search bar so whenever I want to do a search on a URL, I type in google which searches Google for google for me and then I paste the URL into the Google search bar.
Go to Settings -> Manage Search Engines -> Other Search Engines then enter the following 3 fields:
"Google Search Shortcut" "g" "{google:baseURL}search?q=%s"
Now you can just type in "s " (the s key followed by a space) and it will search whatever else you put in there.
I don't actually use this much, but it's there if needed.