Fix boxing/unboxing for generic functions on index expressions

Unsubstituted type should be used for coercion to box value of
 inline class type if it's needed. For the substituted value it's not
 known if it was a generic parameter or not.

 #KT-27502 Fixed

compiler/backend/src/org/jetbrains/kotlin/codegen/ExpressionCodegen.java

@@ -4370,8 +4370,8 @@ public class ExpressionCodegen extends KtVisitor<StackValue, StackValue> impleme
 
             Type elementType = isGetter ? callableMethod.getReturnType() : ArrayUtil.getLastElement(argumentTypes);
             KotlinType elementKotlinType = isGetter ?
-                                           operationDescriptor.getReturnType() :
-                                           CollectionsKt.last(operationDescriptor.getValueParameters()).getType();
+                                           operationDescriptor.getOriginal().getReturnType() :
+                                           CollectionsKt.last(operationDescriptor.getOriginal().getValueParameters()).getType();
             return StackValue.collectionElement(
                     collectionElementReceiver, elementType, elementKotlinType, resolvedGetCall, resolvedSetCall, this
             );

compiler/backend/src/org/jetbrains/kotlin/codegen/StackValue.java

@@ -1449,7 +1449,7 @@ public abstract class StackValue {
 
             Type lastParameterType = ArraysKt.last(setter.getParameterTypes());
             KotlinType lastParameterKotlinType =
-                    CollectionsKt.last(resolvedSetCall.getResultingDescriptor().getValueParameters()).getType();
+                    CollectionsKt.last(resolvedSetCall.getResultingDescriptor().getOriginal().getValueParameters()).getType();
 
             coerce(topOfStackType, topOfStackKotlinType, lastParameterType, lastParameterKotlinType, v);