FIR2IR: change receiver handling in case it's an outer object

Before this commit, FIR2IR expected that FIR will have no receiver
in this case. However, now FIR *has* receiver, so we have to convert
it to object correctly

compiler/testData/codegen/box/objects/classCallsProtectedInheritedByCompanion.kt

@@ -1,4 +1,3 @@
-// IGNORE_BACKEND_FIR: JVM_IR
 open class A {
     protected fun foo() = "OK"
 }