Revert "Union has its associated (nested) tag enum"

This reverts commit d875b4904bbe094728404ee2c9ed512eabcbcaed.

Reason for revert: Patch for verifying b/224692780.

Change-Id: Ie2e698bf5851cead7d3adc942e144fb43d1f1f42
diff --git a/aidl_language.h b/aidl_language.h
index 15ce4bb..f3c5829 100644
--- a/aidl_language.h
+++ b/aidl_language.h
@@ -999,6 +999,10 @@
     return constants_;
   }
   const std::vector<std::unique_ptr<AidlMethod>>& GetMethods() const { return methods_; }
+  void AddMethod(std::unique_ptr<AidlMethod> method) {
+    members_.push_back(method.get());
+    methods_.push_back(std::move(method));
+  }
   const std::vector<const AidlMember*>& GetMembers() const { return members_; }
   void TraverseChildren(std::function<void(const AidlNode&)> traverse) const override {
     AidlAnnotatable::TraverseChildren(traverse);
@@ -1007,17 +1011,6 @@
     }
   }
 
-  // Modifiers
-  void AddMethod(std::unique_ptr<AidlMethod> method) {
-    members_.push_back(method.get());
-    methods_.push_back(std::move(method));
-  }
-  void AddType(std::unique_ptr<AidlDefinedType> type) {
-    type->SetEnclosingScope(this);
-    members_.push_back(type.get());
-    types_.push_back(std::move(type));
-  }
-
  protected:
   // utility for subclasses with getter names
   bool CheckValidForGetterNames() const;