Does dart:ffi Handle have an implicit conversion to bool?

[eseidel]

https://api.dart.dev/stable/3.0.2/dart-ffi/Handle-class.html

Based on usage in Flutter it appears to:
https://github.com/flutter/engine/blob/main/lib/ui/platform_dispatcher.dart#L207
https://github.com/flutter/engine/blob/main/lib/ui/platform_dispatcher.dart#L209

But that's not at all clear from the docs.

(This came up because I appear to have broken this implicit conversion in my FFI hacking, which is likely my bug, but might also just be some bug/quirk in existing FFI that I somehow broke?)
shorebirdtech/shorebird#532 (comment)

[dcharkes]

Handle <-> Object, bool is a valid subtype of Object.

This logic is inconsistent with asFunction because of historical reasons. (@FfiNatives are meant to replace the old native syntax, and that allowed declaring a subtype of the C type.) This is tracked in:

• [vm/ffi] FfiNative return types treatment inconsistent with asFunction #49518