Remove last CJX_ classes that do not meaningfully extend superclasses

Add a comment to cjx_object.h to describe new situation.

Change-Id: I8e5ae815d3f9cad8b022e83dc491a8c0ce07a62a
Reviewed-on: https://pdfium-review.googlesource.com/c/48950
Reviewed-by: Lei Zhang <thestig@chromium.org>
Commit-Queue: Tom Sepez <tsepez@chromium.org>
diff --git a/fxjs/xfa/cjx_boolean.h b/fxjs/xfa/cjx_boolean.h
index ed1f3dd..d2a85ba 100644
--- a/fxjs/xfa/cjx_boolean.h
+++ b/fxjs/xfa/cjx_boolean.h
@@ -7,12 +7,12 @@
 #ifndef FXJS_XFA_CJX_BOOLEAN_H_
 #define FXJS_XFA_CJX_BOOLEAN_H_
 
-#include "fxjs/xfa/cjx_content.h"
+#include "fxjs/xfa/cjx_object.h"
 #include "fxjs/xfa/jse_define.h"
 
 class CXFA_Boolean;
 
-class CJX_Boolean final : public CJX_Content {
+class CJX_Boolean final : public CJX_Object {
  public:
   explicit CJX_Boolean(CXFA_Boolean* node);
   ~CJX_Boolean() override;
@@ -25,7 +25,7 @@
 
  private:
   using Type__ = CJX_Boolean;
-  using ParentType__ = CJX_Content;
+  using ParentType__ = CJX_Object;
 
   static const TypeTag static_type__ = TypeTag::Boolean;
 };