Inability to Convert Dart BigInt to JSBigInt using new js_interop

[maks-yakauleu]

There is currently no straightforward way to convert a Dart BigInt to a JSBigInt using the dart:js_interop package.

Steps to Reproduce:

1. Attempt to pass a Dart BigInt to a JavaScript function that expects a JSBigInt.
2. Observe that there is no built-in method to perform this conversion directly.

Expected Behavior: There should be a built-in method or straightforward way to convert a Dart BigInt to a JSBigInt, similar to how other types like String, num, and List are handled. (toDart, toJS)

Dart 3.4.3 (stable) Flutter 3.22.2 (stable)

[dart-github-bot]

Summary: Users cannot directly convert Dart BigInt to JavaScript BigInt using dart:js_interop. This prevents passing BigInt values to JavaScript functions expecting BigInt arguments.