FIR serializer: fix isLambda copying

compiler/fir/fir2ir/jvm-backend/src/org/jetbrains/kotlin/fir/backend/jvm/FirJvmClassCodegen.kt

@@ -58,7 +58,7 @@ class FirJvmClassCodegen(
             symbol = FirAnonymousFunctionSymbol()
             returnTypeRef = function.returnTypeRef
             receiverTypeRef = function.receiverTypeRef
-            isLambda = false
+            isLambda = (function as? FirAnonymousFunction)?.isLambda == true
             valueParameters.addAll(function.valueParameters)
             typeParameters.addAll(function.typeParameters.filterIsInstance<FirTypeParameter>())
         }

compiler/testData/codegen/box/reflection/lambdaClasses/parameterNamesAndNullability.kt

@@ -1,4 +1,3 @@
-// IGNORE_BACKEND_FIR: JVM_IR
 // TARGET_BACKEND: JVM
 
 // WITH_REFLECT