[jni] Add the ability to check if a JObject is a subclass of a Java class.

[brianquinlan]

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Breaking changes ✔️

Package	Change	Current Version	New Version	Needed Version	Looking good?
jni	Non-Breaking	0.13.0	0.14.0-wip	0.13.1	✔️

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// Copyright (c) 2025, the Dart project authors. Please see the AUTHORS file
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pkgs/jni/lib/src/third_party/generated_bindings.dart
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[coveralls]

coverage: 87.7% (+0.02%) from 87.681%
when pulling a317633 on brianquinlan:check
into 6456d48 on dart-lang:main.

[HosseinYousefi]

Nice changes! Thanks Brian! I added a few small comments.

[HosseinYousefi]

The reason I had used assert here was not to do the type check in release mode.

Fetching the jclass and calling instanceof might be expensive if we perform a lot of castings.

Maybe we can have an unsafe flag which is false by default and if true will not do the checking?

[brianquinlan]

I think that we should be safe by default.

I'd suggest that we do not offer an unsafe option unless we find a need for it. Put I'd be fine having a unsafeCast option, if you'd like me to add one.