lib/html2wt/DOMNormalizer.js
function swappable(a, b) {
	return DOMUtils.numNonDeletedChildNodes(a) === 1 &&
		similar(a, DOMUtils.firstNonDeletedChild(a)) &&
		mergable(DOMUtils.firstNonDeletedChild(a), b);
}
function swappable(a, b) {
	return DOMUtils.numNonDeletedChildNodes(a) === 1 &&
		similar(a, DOMUtils.firstNonDeletedChild(a)) &&
		mergable(DOMUtils.firstNonDeletedChild(a), b);
}
function swappable ( a , b ) { return DOMUtils . numNonDeletedChildNodes ( a ) === 1 && similar ( a , DOMUtils . firstNonDeletedChild ( a ) ) && mergable ( DOMUtils . firstNonDeletedChild ( a ) , b ) ; }
Can a and b be combined into a single node
if we swap a and a.firstChild?

For example: A='<b><i>x</i></b>' b='<i>y</i>' => '<i><b>x</b>y</i>'.
Can a and b be combined into a single node if we swap a and a . firstChild?