You folks do realize she thought he meant she would become black like when it's dark, not black person black. In fact when he said she'd turn like M&M brown she though that was a rather cool idea lol. Nothing really racist about it and as usual, the 4 year old has no concept that people with different color skin are different in any way.

On a personal note when I was a little older than this kid and saw a black and white woman holding hands and asked my mother what color their kids would be and she told me 'polka-dot'. She's not a very racist person, she probably just though it was funny. Me, I believed her until I grew a little older and realized she was full of it.