src/vs/workbench/contrib/scm/browser/dirtydiffDecorator.ts/getChangeHeight
function getChangeHeight(change: IChange): number {
	const modified = change.modifiedEndLineNumber - change.modifiedStartLineNumber + 1;
	const original = change.originalEndLineNumber - change.originalStartLineNumber + 1;

	if (change.originalEndLineNumber === 0) {
		return modified;
	} else if (change.modifiedEndLineNumber === 0) {
		return original;
	} else {
		return modified + original;
	}
}