How to fix contenteditable in Mozilla FireFox?

Question

JavaScript

Good day to all!
There is a div with `contenteditable=true` attribute.
In chrome, when you type text and put a space at the end of the line, it converts it to 

`Hello ` -> `Hello `
`Hello World ` -> `Hello World `
`Hello World` -> `Hello World`

In the mozilla she puts `<br>`instead.  
Is there any way to tell Mozilla that she didn't do that?
I thought at first to use defaultParagraphSeparator + document.execCommand. But I don't have a transfer.