Console completion of a proxy's properties

[Stephan Bergmann]

In the console, when `p` is a `Proxy` object (with a handler that provides an `ownKeys` function), typing `p.` will only provide as completion suggestions the properties of the proxied target object.  It appears to not call the proxy's `ownKeys` handler.

(From looking at the code, I think what's relevant is the

```

while (object.type === 'object' && object.subtype === 'proxy')

```

loop getting at `[[Target]]` in `completePropertiesInner` in `front_end/ui/components/text_editor/javascript.ts` in the <https://github.com/ChromeDevTools/devtools-frontend> repo.)

I wonder what the rationale is for that, and whether there would be some way the proxy could provide its own completion suggestions dynamically?