Change color effect doesn't work the same as in Scratch 2.0 on white

[fsih]

Expected Behavior

White is slightly tinted so that the change color effect will be visible

Actual Behavior

In Scratch 3.0, white stays white

Steps to Reproduce

Change color effect on a white sprite
See https://scratch.mit.edu/projects/182266032/
https://llk.github.io/scratch-gui/develop/#182266032

[adroitwhiz]

I can't reproduce this--it seems to have been fixed by #355