Admit implicit arguments object updates

[rogeralsing]

Summary

• Admit bounded implicit arguments object updates such as arguments++ through production unified bytecode.
• Reuse the existing dynamic identifier update opcode now that the production route materializes the arguments binding.
• Make typeof arguments use the dynamic binding path when the bounded arguments-object lane is active, preserving correctness after arguments is reassigned.

Verification

• rtk dotnet test tests/Asynkron.JsEngine.Tests -c Release --filter 'FullyQualifiedNameUnifiedBytecodeProductionEligibilityTests.Evaluate_UpdateImplicitArgumentsObject_AcceptsDynamicIdentifierUpdate|FullyQualifiedNameUnifiedBytecodeProductionEligibilityTests.Evaluate_ArgumentsAccess_AcceptsImplicitArgumentsObjectRead|FullyQualifiedNameUnifiedBytecodeProductionEligibilityTests.Evaluate_TypeOfImplicitArgumentsObject_AcceptsObjectType|FullyQualifiedNameUnifiedBytecodeProductionEligibilityTests.Evaluate_CallImplicitArgumentsObject_DeclinesWithArgumentsDependency|FullyQualifiedNameUnifiedBytecodeProductionInvocationTests.UpdateImplicitArgumentsObject_UsesUnifiedBytecodeProductionFastPath|FullyQualifiedNameUnifiedBytecodeProductionInvocationTests.ImplicitArgumentsObjectRead_UsesUnifiedBytecodeProductionFastPath|FullyQualifiedName~UnifiedBytecodeProductionInvocationTests.TypeOfImplicitArgumentsObject_UsesUnifiedBytecodeProductionFastPath'
• rtk dotnet test tests/Asynkron.JsEngine.Tests -c Release --filter 'FullyQualifiedNameUnifiedBytecodeProductionEligibilityTests|FullyQualifiedNameUnifiedBytecodeProductionInvocationTests|FullyQualifiedNameUnifiedBytecodeProductionSpreadCallTests|FullyQualifiedNameUnifiedBytecodeProductionConstructCallTests|FullyQualifiedNameExpressionProgramLoweringTests|FullyQualifiedNameExpressionProgramCoverageMapTests|FullyQualifiedName~AstFreeExecutionAssertionTests'
• rtk dotnet build src/Asynkron.JsEngine/Asynkron.JsEngine.csproj -c Release
• rtk rg 'EvaluateExpression(|ProfileEvaluateExpression(' src/Asynkron.JsEngine/Ast/TypedAstEvaluator.ExecutionPlanRunner*
• rtk git diff --check

[Copilot]

Pull request overview

This PR expands production unified-bytecode routing to correctly handle implicit arguments identifier updates (e.g., arguments++) by reusing the existing dynamic-identifier update opcode, and ensures typeof arguments stays correct when arguments is reassigned under the bounded arguments-object lane.

Changes:

• Admit UpdateIdentifier operations on the implicit arguments binding when ordinary dynamic identifier environment operations are enabled.
• Route typeof arguments through TypeOfDynamicIdentifier when the bounded arguments-object dynamic-identifier lane is active (otherwise keep the "object" literal fast-path).
• Update eligibility/invocation tests and the unified-bytecode expansion contract documentation to reflect the new admitted shapes.

Reviewed changes

Copilot reviewed 6 out of 6 changed files in this pull request and generated 1 comment.

Show a summary per file

File	Description
tests/Asynkron.JsEngine.Tests/UnifiedBytecodeProductionInvocationTests.cs	Updates invocation test to expect the unified-bytecode production fast path for arguments++ and verify runtime semantics after reassignment.
tests/Asynkron.JsEngine.Tests/UnifiedBytecodeProductionEligibilityTests.cs	Updates eligibility tests to accept implicit arguments update via dynamic identifier ops and adjusts typeof arguments assertions.
src/Asynkron.JsEngine/Execution/UnifiedBytecode/UnifiedBytecodeProductionEligibility.cs	Broadens the implicit-arguments dependency scan to include identifier updates and relaxes update-expression decline when dynamic identifiers are allowed.
src/Asynkron.JsEngine/Execution/UnifiedBytecode/UnifiedBytecodeCompiler.cs	Allows arguments updates to compile to UpdateDynamicIdentifier and conditionally routes typeof arguments via dynamic identifier lookup.
src/Asynkron.JsEngine/Ast/TypedAstEvaluator.SyncFunctionInvoker.cs	Switches to the renamed/expanded implicit-arguments dependency helper to gate the bounded arguments-object dynamic-identifier lane.
docs/unified-bytecode-expansion-contract.md	Updates the contract text to reflect that implicit arguments reads/updates are admitted and typeof arguments uses the bounded route.

---

💡 Add Copilot custom instructions for smarter, more guided reviews. Learn how to get started.