[minor] unmute fixed FIR tests

compiler/testData/ir/irText/declarations/multiplatform/expectClassInherited.kt

@@ -1,4 +1,3 @@
-// IGNORE_BACKEND_FIR: JVM_IR
 // !LANGUAGE: +MultiPlatformProjects
 
 expect abstract class A protected constructor() {

compiler/testData/ir/irText/declarations/multiplatform/expectedEnumClass.kt

@@ -1,4 +1,3 @@
-// IGNORE_BACKEND_FIR: JVM_IR
 // !LANGUAGE: +MultiPlatformProjects
 
 expect enum class MyEnum {

idea/testData/checker/ResolveTypeInAnnotationArgumentRuntime.kt

@@ -1,4 +1,5 @@
 // IGNORE_DUPLICATED_FIR_SOURCE_EXCEPTION
+// FIR_COMPARISON
 import kotlin.reflect.KClass
 
 annotation class Ann(val value: KClass<*>)