Prohibit non-inner classes in enum entries since 1.3

compiler/testData/diagnostics/tests/inner/innerClassInEnumEntryClass_lv13.kt

@@ -0,0 +1,19 @@
+// !LANGUAGE: +InnerClassInEnumEntryClass +NestedClassesInEnumEntryShouldBeInner
+
+enum class Enum {
+    ENTRY_WITH_CLASS {
+        inner class TestInner
+
+        <!NESTED_CLASS_NOT_ALLOWED!>class TestNested<!>
+
+        <!NESTED_CLASS_NOT_ALLOWED!>interface TestInterface<!>
+
+        <!NESTED_CLASS_NOT_ALLOWED!>object TestObject<!>
+
+        <!NESTED_CLASS_NOT_ALLOWED!>enum class TestEnumClass<!> {
+            OTHER_ENTRY
+        }
+
+        <!WRONG_MODIFIER_CONTAINING_DECLARATION!>companion<!> object {}
+    }
+}