Element closing tag spans

[gbj]

We get pretty good syntax highlighting with our syn-rsx-based view macro in Leptos. Here's an example from VS Code:

The only issue is that closing tags are simply highlighted as plain identifiers, so a PascalCase component name looks like a struct, and a lowercased HTML element looks like a variable. I can imagine some ways I could improve this, but they rely on having access to the span of the closing tag. Unless I'm mistaken, the NodeName you can get from NodeElement::name() gives you the opening span, but there's not a way to get the span of the closing tag, if it exists.