Floating label active text color.

I'm trying to implement text field "error" state by setting color to
`floatingLabelActiveTextColor` and `floatingLabelTextColor` properties.
Color of floating label sometimes not changing until field becomes first responder.

Start by reproducing the floating-label color behavior using the floatingLabelActiveTextColor and floatingLabelTextColor properties on the UITextField subclass. Trace when these properties are applied relative to the field becoming first responder. Done means the label color updates consistently for the error state without requiring the field to become first responder.

Written by the indexing model from the issue text.