Backported from 1eda18365a
NgModel will format all scope-based values to string when setting the viewValue for
the associated input element. The formatting, however, only applies to input elements
that contain a text, email, url or blank input type. In the event of a null or undefined
scope or model value, the viewValue will be set to null or undefined instead of being
converted to an empty string.
Closes#5936Closes#9277
Caitlin Potter
1b8b41ad23