Evaluated variables that are DOM elements do not have any fields/getters

Moving this from https://github.com/Dart-Code/Dart-Code/issues/4673 as it feels like a DWDS issue.

When hitting a breakpoint and looking at local variables (which come from the `topFrame`), variables that are DOM elements do not contain any `fields` like a standard class would.

When we walk up the class hierarchy looking for getters, we also find no getters - but I do see fields on the superclasses:

```
<== {
"jsonrpc": "2.0",
"result": {
// ...
"fields": [
{
"type": "@Field",
"id": "742",
"name": "mouseWheelEvent",
// ...
},
```

In the VM, fields from superclasses show up on the variable, so this seems like a difference. I think if these fields are really fields they should be on the variable itself, or if they are considered getters they should be marked as such (instead of fields).

Start by tracing how DWDS exposes local variables from the topFrame and how it maps DOM-element fields and getters in the JSON-RPC response. Compare this behavior with the VM, then confirm that DOM-element variables consistently expose inherited fields or getters as intended.

Written by the indexing model from the issue text.