Safari: RangeError: Maximum call stack size exceeded.

I'm not sure if it's valid to use br as a defaultParagraphSeparator, but when using that it generates an error on Safari on this line:

if (firstChild && firstChild.nodeType === 3) exec(formatBlock, '<' + defaultParagraphSeparator + '>');else if (content.innerHTML === '<br>')

It seems to work okay in other browsers.