Admit default derived constructors to production bytecode

[rogeralsing]

Summary

• admit synthetic default-derived constructors to the production unified bytecode route
• bind the generated rest parameter as a JsArray for production slots and constructor environments
• forward default-derived super(...args) from the rest array without invoking iterator spread semantics
• remove the stale default-derived production pre-gate docs row

Verification

• rtk dotnet test tests/Asynkron.JsEngine.Tests -c Release --filter 'FullyQualifiedNameUnifiedBytecodeProductionConstructCallTests.DefaultDerivedConstructor_UsesProductionFastPath|FullyQualifiedNameUnifiedBytecodeProductionConstructCallTests.DefaultDerivedConstructor_ForwardsArgumentsWithoutIteratorProtocol|FullyQualifiedNameUnifiedBytecodeProductionConstructCallTests.SuperConstructWithSpread_UsesProductionFastPath|FullyQualifiedNameUnifiedBytecodeProductionConstructCallTests.SuperConstruct_InitializesThis|FullyQualifiedNameUnifiedBytecodeProductionEligibilityTests.Evaluate_DefaultDerivedConstructor_AcceptsSuperConstructInvocationBoundary|FullyQualifiedNameExpressionProgramCoverageMapTests.UnifiedBytecodeExpansionContract_ListsRequiredHeadingsAndCurrentEnums'
• rtk dotnet test tests/Asynkron.JsEngine.Tests -c Release --filter 'FullyQualifiedName~UnifiedBytecodeProductionConstructCallTests'
• rtk dotnet test tests/Asynkron.JsEngine.Tests -c Release --filter 'FullyQualifiedName~UnifiedBytecodeProduction'
• rtk dotnet test tests/Asynkron.JsEngine.Tests -c Release --filter 'FullyQualifiedName~ActivationSemanticsProofPackTests'
• rtk rg 'EvaluateExpression(|ProfileEvaluateExpression(' src/Asynkron.JsEngine/Ast/TypedAstEvaluator.ExecutionPlanRunner*
• rtk dotnet build Asynkron.JsEngine.sln -c Release
• rtk ./tools/profile forloop --memory

[Copilot]

Pull request overview

This PR expands the production unified-bytecode “construct” fast path to include synthetic default-derived constructors (i.e., class Derived extends Base {}), ensuring their implicit super(...args) behavior is handled efficiently and with the intended argument-forwarding semantics.

Changes:

• Admits default-derived constructors into the production unified-bytecode eligibility/fast-path flow (including the super-construct invocation boundary).
• Binds the synthetic rest parameter as a JsArray in production slots/environments and forwards super(...args) by extracting items directly (avoiding generic spread materialization).
• Updates tests and the unified-bytecode expansion contract docs to reflect the new admission rules (and removes the stale pre-gate entry).

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/UnifiedBytecodeProductionEligibilityTests.cs	Adds eligibility coverage to ensure default-derived constructors can pass production gating and include the super-construct boundary + spread masks.
tests/Asynkron.JsEngine.Tests/UnifiedBytecodeProductionConstructCallTests.cs	Updates/extends construct-call tests to assert default-derived constructors take the production fast path and validate forwarding behavior expectations.
tests/Asynkron.JsEngine.Tests/ExpressionProgramCoverageMapTests.cs	Removes the “pre-gate:IsDefaultDerivedConstructor” heading expectation to match the updated contract/gating model.
src/Asynkron.JsEngine/Execution/UnifiedBytecode/UnifiedBytecodeVirtualMachine.cs	Adds a specialized forwarding path for default-derived super(...args) to avoid generic spread materialization.
src/Asynkron.JsEngine/Ast/TypedAstEvaluator.SyncFunctionInvoker.cs	Adjusts production-slot/environment parameter binding to support a synthetic rest argument array for default-derived constructors and admits the new parameter shape.
docs/unified-bytecode-expansion-contract.md	Updates contract text to document default-derived constructor admission and removes the stale pre-gate row.

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