Remove uses of .__proto__ from JS code

[annagrin]

We currently have a case where we call __proto__ to determine if the object is a plain JS object:

Use of __proto__ should be replaced by Object.getPrototypeOf(#)`. Or maybe we can use the object runtime metadata to determine its type?

See more information in dart-lang/sdk#52372

webdev/dwds/lib/src/debugging/inspector.dart

Line 219 in 2b2ae0e

if (!(this.__proto__)) { return 'Instance of PlainJavaScriptObject';}

[jyameo]

Is this a duplicate issue of dart-lang/sdk#52372? Looks like the issue has already been closed.

[bkonyi]

I don't think so. There's still references to this.__proto__ in DWDS.