Fix codegen tests after types enhancement

compiler/testData/codegen/box/builtinStubMethods/extendJavaCollections/abstractMap.kt

@@ -2,7 +2,7 @@ import java.util.AbstractMap
 import java.util.Collections
 
 class A : AbstractMap<Int, String>() {
-    override fun entrySet(): Set<Map.Entry<Int, String>> = Collections.emptySet()
+    override fun entrySet(): MutableSet<MutableMap.MutableEntry<Int, String>> = Collections.emptySet()
 }
 
 fun box(): String {

compiler/testData/codegen/boxWithStdlib/reflection/enclosing/kt6368.kt

@@ -15,7 +15,7 @@ val a by Delegates.lazy {
 }
 
 fun box(): String {
-    val r = a["result"]
+    val r = a["result"]!!
 
     // Check that reflection won't fail
     r.javaClass.getEnclosingMethod().toString()