Fix a problem after using highlightAll text was not replaced correctly

[amlynarczyk]

After using select all, when typing anything, the string entered is "/" because previous version of completionRange is used, which always begin on 0

Actual string during textDidChange is [NEWPART][HIGHLIGHTEDPART], for example when string was "facebook.com/" when textDidChange is called after pressing q, string is "qfacebook.com/" so the completionRange location should be moved by the difference of currrentText length.