fixed replaceChild bug

[Gcaufy]

// node: <div><slot /></div>
// newChild: Hello World
// oldChild: <slot />

node.replaceChild(newChild, oldChild);

// Expect: <div>Hello World</div>
// Actually: Hello World

But if I added a space befor <slot />, I get the correct result.

// node: <div> <slot /></div>
// newChild: Hello World
// oldChild: <slot />

node.replaceChild(newChild, oldChild);

// Expect: <div> Hello World</div>
// Actually: <div> Hello World</div>

[songkeys]

It keeps reporting:

TypeError: Cannot read property 'parentNode' of null

Should be:

if (nextChild != null) {
	nextChild.parentNode.firstChild = newFirst;
}else{
	parentNode.firstChild = newFirst;
}