fix(KT-49225): remove unnecessery boxing.

compiler/ir/backend.js/src/org/jetbrains/kotlin/ir/backend/js/lower/ExportedDefaultParameterStub.kt

@@ -41,7 +41,7 @@ class ExportedDefaultParameterStub(val context: JsIrBackendContext) : Declaratio
             irIfThenElse(
                 toParameter.type,
                 irEqeqeq(
-                    irGet(toParameter),
+                    irGet(toParameter, context.irBuiltIns.anyNType),
                     irCall(this@ExportedDefaultParameterStub.context.intrinsics.jsUndefined)
                 ),
                 defaultValue.expression,

compiler/ir/ir.tree/src/org/jetbrains/kotlin/ir/builders/ExpressionHelpers.kt

@@ -128,6 +128,8 @@ fun IrBuilderWithScope.irGet(type: IrType, variable: IrValueSymbol) =
 
 fun IrBuilderWithScope.irGet(variable: IrValueDeclaration) = irGet(variable.type, variable.symbol)
 
+fun IrBuilderWithScope.irGet(variable: IrValueDeclaration, type: IrType) = irGet(type, variable.symbol)
+
 fun IrBuilderWithScope.irSet(variable: IrValueSymbol, value: IrExpression, origin: IrStatementOrigin = IrStatementOrigin.EQ) =
     IrSetValueImpl(startOffset, endOffset, context.irBuiltIns.unitType, variable, value, origin)