Don't autoselect first item in dropdown

Bug 6434183

When in phone mode and the user types something that happens to bring up
the dropdown, don't auto-select the first item if they don't choose
something. This was preventing users from entering numbers and shortcuts
that happened to be close matches to existing contacts. Unless the user
selects an item, keep what they manually entered. The change looks much
bigger than is really is. The only real change is in commitChip. The rest
of the changes are to call a helper function, rather than duplicating the
same code throughout the file.

Change-Id: Ia0ec24a3667770fa5d43ff870ed87019b732627e