M.updateTextFields() not adding valid class on prefilled text fields

[leftdead7]

Materialize Release: 1.0.0-alpha.4
Chrome Version 65.0.3325.181 (Official Build) (64-bit)
Windows 10 desktop

##description
When an input field with some value in it, goes out of focus, the bottom border retains its color.
But when M.updateTextFields() is called for prefilled text field it does not adds the valid class to it and hence the bottom border color remains grey

Expected Behavior

After calling M.updateTextFields(), valid class to be added to prefilled inputs so that the bottom border is colored.

Steps to Reproduce (for bugs)

The same can be reproduced on Materializecss website in the "Prefilling Text Inputs" section

[Abolfazl]

I am having this same issue. It would be nice to have it automatically show the valid/invalid CSS class for prefilled text inputs.