Select/Autocompleter: don't erase incorrect input

[bill]

If user types in an invalid value, and tabs away, we'll just leave the text they typed in the <input> box.   We won't erase the value, nor revert to the last good value, not ignore user keystrokes that cause the text to become invalid (ie, if the user types "californib" or "acalifornia", all the characters will go into the input box).

While this doesn't match the behavior of a browser's <select> or OS drop down, my judgement is that it's the best option, since we don't lose any data the user typed in. It also works well with the asynchronous nature of dojo.data, which prevents us from immediately determining if a given string is valid or invalid.

[doughays]

(In [8928]) Fixes #3268. Proxy commit for haysmark. If you enter invalid text into a FilteredSelect? box, the widget will keep the bad text and the old hidden value.