[Native] Drop getContainingFile from IrUtils2

We can reuse `fileOrNull` function from common `IrUtils`

kotlin-native/backend.native/compiler/ir/backend.native/src/org/jetbrains/kotlin/backend/konan/descriptors/ClassLayoutBuilder.kt

@@ -467,7 +467,7 @@ internal class ClassLayoutBuilder(val irClass: IrClass, val context: Context) {
         val result = mutableMapOf<IrClass, IrClass>()
 
         irClass.annotations.forEach {
-            val irFile = irClass.getContainingFile()
+            val irFile = irClass.fileOrNull
 
             val annotationClass = (it.symbol.owner as? IrConstructor)?.constructedClass
                     ?: error(irFile, it, "unexpected annotation")

kotlin-native/backend.native/compiler/ir/backend.native/src/org/jetbrains/kotlin/backend/konan/llvm/objcexport/ObjCExportCodeGenerator.kt

@@ -1142,11 +1142,11 @@ private fun ObjCExportCodeGenerator.effectiveThrowsClasses(method: IrFunction, s
     val throwsVararg = throwsAnnotation.getValueArgument(0)
             ?: return emptyList()
 
-    if (throwsVararg !is IrVararg) error(method.getContainingFile(), throwsVararg, "unexpected vararg")
+    if (throwsVararg !is IrVararg) error(method.fileOrNull, throwsVararg, "unexpected vararg")
 
     return throwsVararg.elements.map {
         (it as? IrClassReference)?.symbol?.owner as? IrClass
-                ?: error(method.getContainingFile(), it, "unexpected @Throws argument")
+                ?: error(method.fileOrNull, it, "unexpected @Throws argument")
     }
 }
 

kotlin-native/backend.native/compiler/ir/backend.native/src/org/jetbrains/kotlin/backend/konan/optimizations/DataFlowIR.kt

@@ -509,7 +509,7 @@ internal object DataFlowIR {
                 type.vtable += layoutBuilder.vtableEntries.map {
                     val implementation = it.getImplementation(context)
                             ?: error(
-                                    irClass.getContainingFile(),
+                                    irClass.fileOrNull,
                                     irClass,
                                     """
                                         no implementation found for ${it.overriddenFunction.render()}
@@ -524,7 +524,7 @@ internal object DataFlowIR {
                     type.itable[iface.classId] = iface.interfaceVTableEntries.map {
                         val implementation = layoutBuilder.overridingOf(it)
                                 ?: error(
-                                        irClass.getContainingFile(),
+                                        irClass.fileOrNull,
                                         irClass,
                                         """
                                             no implementation found for ${it.render()}

kotlin-native/backend.native/compiler/ir/backend.native/src/org/jetbrains/kotlin/ir/util/IrUtils2.kt

@@ -97,16 +97,6 @@ inline fun <reified T> stub(name: String): T {
     } as T
 }
 
-tailrec fun IrDeclaration.getContainingFile(): IrFile? {
-    val parent = this.parent
-
-    return when (parent) {
-        is IrFile -> parent
-        is IrDeclaration -> parent.getContainingFile()
-        else -> null
-    }
-}
-
 fun IrFunctionAccessExpression.addArguments(args: Map<IrValueParameter, IrExpression>) {
     val unhandledParameters = args.keys.toMutableSet()
     fun getArg(parameter: IrValueParameter) = args[parameter]?.also { unhandledParameters -= parameter }