Support innerHTML in serialization recipe

I understand you don't want to support serialization in this project which makes sense. However, when experimenting with the example recipe I've noticed an issue when serializing the document after Preact mutates it. I end up with elements that have both innerHTML and childNodes[] defined. The innerHTML value seems to have not been cleaned up. I'm not sure where or why this is happening exactly. Any thoughts?

I've added innerHTML and void elements to my implementation here: https://gist.github.com/Stanback/3bb0b19b299668ce0e08922a8ab6876e

从示例序列化方案开始，重现 Preact 修改文档的情况，并使 innerHTML 和 childNodes[] 都保持已定义。将序列化输出与 gist 实现进行比较，重点关注 innerHTML 和 void elements。完成的标准是：修改后，序列化不再保留过时的 innerHTML。

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