Make IntermediateNodeCollection implement IReadOnlyList<IntermediateNode>

[Copilot]

Summary of the changes

• IntermediateNodeCollection already had Count and an indexed getter but didn't declare IReadOnlyList<IntermediateNode>, blocking standard LINQ and list-pattern usage on Children collections.

• Added IReadOnlyList<IntermediateNode> to the interface list — no new members needed, purely additive.

Enables patterns like:

// Previously required custom helpers
node.Children.All(c => c is HtmlIntermediateToken)

// Or list patterns
if (node.Children is [HtmlIntermediateToken])

Warning

Firewall rules blocked me from connecting to one or more addresses (expand for details)

I tried to connect to the following addresses, but was blocked by firewall rules:

• st8vsblobprodcus339.vsblob.vsassets.io
  • Triggering command: /usr/share/dotnet/dotnet dotnet build src/Compiler/Microsoft.CodeAnalysis.Razor.Compiler/src/Microsoft.CodeAnalysis.Razor.Compiler.csproj (dns block)

If you need me to access, download, or install something from one of these locations, you can either:

• Configure Actions setup steps to set up my environment, which run before the firewall is enabled
• Add the appropriate URLs or hosts to the custom allowlist in this repository's Copilot coding agent settings (admins only)

[ToddGrun]

Are there some places we can change to take advantage of this, or is that coming later?

[chsienki]

Yeah there are places. It'll be a follow up just because of the way I broke up the github issues.