Use 'evt.shiftKey' instead of matching 'charCodes'

The shortcut wasn't running consistently and was blocking
'Cmd+L' on Chrome 38. Instead of going to the location bar
it would tooggle the list. Strangely, it did not override
'Cmd+N'. Using `evt.shiftKey` instead of matching the `charCode`
to the uppercase letter solves the problem.
Merge pull request #2271 from prtksxna/keyboard-error

Use 'evt.shiftKey' instead of matching 'charCodes'