Fix: Skip hidden inputs before text instance

[acdlite]

Found a hydration bug that happens when you pass a Server Action to formAction and the next node is a text instance.

The HTML generated by Fizz is something like this:

<button name="$ACTION_REF_5" formAction="" formEncType="multipart/form-data" formMethod="POST">
  <input type="hidden" name="$ACTION_5:0" value="..."/>
  <input type="hidden" name="$ACTION_5:1" value="..."/>
  <input type="hidden" name="$ACTION_KEY" value="..."/>Count: <!-- -->0
</button>

Fiber is supposed to skip over the extra hidden inputs, but it doesn't handle this correctly if the next expected node isn't a host instance. In this case, it's a text instance.

Not sure if the proper fix is to change the HTML that is generated, or to change the hydration logic, but in this PR I've done the latter.

[react-sizebot]

Comparing: 627b7ab...4a0ca0f

Critical size changes

Includes critical production bundles, as well as any change greater than 2%:

Name	+/-	Base	Current	+/- gzip	Base gzip	Current gzip
oss-stable/react-dom/cjs/react-dom.production.min.js	=	165.63 kB	165.63 kB	=	51.88 kB	51.88 kB
oss-experimental/react-dom/cjs/react-dom.production.min.js	+0.03%	174.82 kB	174.88 kB	+0.02%	54.69 kB	54.70 kB
facebook-www/ReactDOM-prod.classic.js	=	570.44 kB	570.44 kB	=	100.45 kB	100.45 kB
facebook-www/ReactDOM-prod.modern.js	=	554.21 kB	554.21 kB	=	97.61 kB	97.61 kB

Significant size changes

Includes any change greater than 0.2%:

(No significant changes)

Generated by 🚫 dangerJS against 4a0ca0f