[IR] Make IrValueSymbol a sealed interface

compiler/ir/ir.tree/src/org/jetbrains/kotlin/ir/symbols/IrSymbol.kt

@@ -80,7 +80,7 @@ interface IrScriptSymbol : IrClassifierSymbol, IrBindableSymbol<ScriptDescriptor
 
 interface IrTypeParameterSymbol : IrClassifierSymbol, IrBindableSymbol<TypeParameterDescriptor, IrTypeParameter>, TypeParameterMarker
 
-interface IrValueSymbol : IrSymbol {
+sealed interface IrValueSymbol : IrSymbol {
     @ObsoleteDescriptorBasedAPI
     override val descriptor: ValueDescriptor
 

compiler/ir/ir.tree/src/org/jetbrains/kotlin/ir/util/DeepCopySymbolRemapper.kt

@@ -213,7 +213,6 @@ open class DeepCopySymbolRemapper(
         when (symbol) {
             is IrValueParameterSymbol -> valueParameters.getReferenced(symbol)
             is IrVariableSymbol -> variables.getReferenced(symbol)
-            else -> throw IllegalArgumentException("Unexpected symbol $symbol")
         }
 
     override fun getReferencedFunction(symbol: IrFunctionSymbol): IrFunctionSymbol =