Fixes #9667: allow Edge and IE child windows to use Text Components

[kenotron]

Fixes #9667

Appending a child (insertBefore) with a documentFragment apparently isn't supported in IE / Edge. I've added code to simply skip this node and just let the tree walking algo add the nodes below.

[gaearon]

This code is not used on master (React 16 comes out very soon and won't use it). Can you check if the issue still occurs with 16 RC3?

[kenotron]

Oh, things are even more busted in React 16 actually. That's bad :( I'm going to try to isolate where we can fix this. I think basically we need to be aware that we're about about to insert an entire documentfragment across documents. Where would THAT code be?

[kenotron]

I'm not familiar enough with Fiber to get to the bottom of it all, but basically in
appendInitialChild, the parentInstance and the child are actually coming from different ownerDocuments if it's a child window. Somehow somewhere IE / Edge fell through the cracks and a child gets created inside the parent window document and the reconciler tries to append that child from parent to child window. Other browsers seem to handle this okay, but not in IE / Edge...

[kenotron]

@gaearon a little assist?

[kenotron]

Okay, I found a genuine bug inside createTextNode - it is always assuming to create a text node from inside window.document rather than a host instance's ownerDocument...