Unwrap Proxy receivers and arguments before Java dispatch

[edusperoni]

Description

Java object wrappers wrapped in a JS Proxy — which is what Vue 3's reactive() does to anything stored in component data() — expose no internal fields and no creation context, so the runtime could not find the Java object behind them. Reproduced on main with a bare new Proxy(new java.lang.StringBuilder(), {}):

Call through a Proxy	Before
proxy.append("x")	process abort: # Fatal error in v8::Object::GetInternalField() / Internal field out of bounds (MetadataNode::MethodCallback reads CallSuper off info.This())
any private-value lookup on a Proxy (V8GetPrivateValue/V8SetPrivateValue)	process abort in GetCreationContext().ToLocalChecked() — a Proxy never has a creation context

Vue 3 users have been working around this with markRaw/toRaw.

Changes

• ObjectManager::UnwrapProxy follows Proxy-of-Proxy chains to the target (null when revoked). GetJSInstanceInfo — and therefore every GetJavaObjectByJsObject caller (arg converters, FieldAccessor, ArrayElementAccessor, instanceof, Interop, NativeScriptException, ArrayHelper) — resolves through it.
• Method, field, super, class and null accessors dispatch on the Proxy target exactly as on a direct receiver. A revoked Proxy, or one whose target is not a Java object for an instance member, throws a catchable TypeError. CallSuper is read only from objects that actually carry the field, so a plain object as this now throws the existing "no Java counterpart" error instead of aborting.
• JsArgConverter, JsArgToArrayConverter, JSToJavaConverter and MethodCache::GetType marshal the target of a Proxy argument, so proxied Java objects and proxied JS arrays (and their elements) convert as their targets do; a revoked Proxy argument is a conversion error.
• Implementation objects passed to extend() / interface constructors are unwrapped.
• GetCreationContextOrCurrent replaces every GetCreationContext(...).ToLocalChecked(); Symbol.hasInstance gets the standard try/catch → ReThrowToV8; URLImpl::GetPointer checks the internal-field count first.

Proxy traps are consulted only for the JS-side lookup; the Java call runs on the target.

Does your commit message include the wording below to reference a specific issue in this repo?

No linked issue (reported through nativescript-vue; root-caused in the runtime).

Related Pull Requests

• iOS counterpart with identical semantics: fix(runtime): unwrap Proxy receivers and arguments before native dispatch ios#485

Does your pull request have unit tests?

Yes — test-app/app/src/main/assets/app/tests/testProxyReceivers.js, 16 specs (instance/trap/nested/static receivers, public field get/set, string coercion, proxied object/array/element arguments, array element assignment, revoked receiver and argument, non-Java target, plain-object receiver, instanceof, extended-class override + super). Full suite on the emulator: 1258 passed / 0 failed (main: 1242 / 0).

Shared-submodule versions of these specs can follow once both runtimes land.

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