FIR2IR: correct dispatch receiver inside inner class constructor

compiler/fir/fir2ir/src/org/jetbrains/kotlin/fir/backend/Fir2IrConversionScope.kt

@@ -118,6 +118,11 @@ class Fir2IrConversionScope {
     fun dispatchReceiverParameter(irClass: IrClass): IrValueParameter? {
         for (function in functionStack.asReversed()) {
             if (function.parentClassOrNull == irClass) {
+                // An inner class's constructor needs an instance of the outer class as a dispatch receiver.
+                // However, if we are converting `this` receiver inside that constructor, now we should point to the inner class instance.
+                if (function is IrConstructor && irClass.isInner) {
+                    irClass.thisReceiver?.let { return it }
+                }
                 function.dispatchReceiverParameter?.let { return it }
             }
         }

compiler/testData/codegen/box/secondaryConstructors/innerClasses.kt

@@ -1,4 +1,3 @@
-// IGNORE_BACKEND_FIR: JVM_IR
 class Outer {
     val outerProp: String
     constructor(x: String) {

compiler/testData/codegen/box/secondaryConstructors/innerClassesInheritance.kt

@@ -1,4 +1,3 @@
-// IGNORE_BACKEND_FIR: JVM_IR
 class Outer {
     val outerProp: String
     constructor(x: String) {