Allow modifier 'inner' on a class nested in enum entry class

compiler/testData/diagnostics/tests/inner/innerClassInEnumEntryClass_lv11.kt

@@ -1,4 +1,4 @@
-// LANGUAGE_VERSION: 1.1
+// !LANGUAGE: -InnerClassInEnumEntryClass
 
 enum class Enum {
     ENTRY_WITH_CLASS {

compiler/testData/diagnostics/tests/inner/innerClassInEnumEntryClass_lv12.kt

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

compiler/testData/diagnostics/tests/inner/innerClassInEnumEntryClass_lv12.txt

@@ -0,0 +1,20 @@
+package
+
+public final enum class Enum : kotlin.Enum<Enum> {
+    enum entry ENTRY_WITH_CLASS
+
+    private constructor Enum()
+    public final override /*1*/ /*fake_override*/ val name: kotlin.String
+    public final override /*1*/ /*fake_override*/ val ordinal: kotlin.Int
+    protected final override /*1*/ /*fake_override*/ fun clone(): kotlin.Any
+    public final override /*1*/ /*fake_override*/ fun compareTo(/*0*/ other: Enum): kotlin.Int
+    public final override /*1*/ /*fake_override*/ fun equals(/*0*/ other: kotlin.Any?): kotlin.Boolean
+    protected/*protected and package*/ final override /*1*/ /*fake_override*/ /*isHiddenForResolutionEverywhereBesideSupercalls*/ fun finalize(): kotlin.Unit
+    public final override /*1*/ /*fake_override*/ /*isHiddenForResolutionEverywhereBesideSupercalls*/ fun getDeclaringClass(): java.lang.Class<Enum!>!
+    public final override /*1*/ /*fake_override*/ fun hashCode(): kotlin.Int
+    public open override /*1*/ /*fake_override*/ fun toString(): kotlin.String
+
+    // Static members
+    public final /*synthesized*/ fun valueOf(/*0*/ value: kotlin.String): Enum
+    public final /*synthesized*/ fun values(): kotlin.Array<Enum>
+}