--- a/editor/libeditor/EditAction.h
+++ b/editor/libeditor/EditAction.h
@@ -109,18 +109,20 @@ enum class EditSubAction : int32_t
   // source and insert into the DOM tree.  So, this is similar to innerHTML.
   eInsertHTMLSource,
 
   // eSetPositionToAbsolute and eSetPositionToStatic indicate to set position
   // property to absolute or static.
   eSetPositionToAbsolute,
   eSetPositionToStatic,
 
-  decreaseZIndex,
-  increaseZIndex,
+  // eDecreaseZIndex and eIncreaseZIndex indicate to decrease and increase
+  // z-index value.
+  eDecreaseZIndex,
+  eIncreaseZIndex,
 };
 
 } // namespace mozilla
 
 inline bool operator!(const mozilla::EditSubAction& aEditSubAction)
 {
   return aEditSubAction == mozilla::EditSubAction::eNone;
 }

--- a/editor/libeditor/HTMLAbsPositionEditor.cpp
+++ b/editor/libeditor/HTMLAbsPositionEditor.cpp
@@ -141,26 +141,26 @@ HTMLEditor::SetZIndex(Element& aElement,
 
 nsresult
 HTMLEditor::AddZIndex(int32_t aChange)
 {
   AutoPlaceholderBatch beginBatching(this);
   AutoTopLevelEditSubActionNotifier maybeTopLevelEditSubAction(
                                       *this,
                                       aChange < 0 ?
-                                        EditSubAction::decreaseZIndex :
-                                        EditSubAction::increaseZIndex,
+                                        EditSubAction::eDecreaseZIndex :
+                                        EditSubAction::eIncreaseZIndex,
                                       nsIEditor::eNext);
 
   // brade: can we get rid of this comment?
   // Find out if the selection is collapsed:
   RefPtr<Selection> selection = GetSelection();
   NS_ENSURE_TRUE(selection, NS_ERROR_NULL_POINTER);
-  EditSubActionInfo subActionInfo(aChange < 0 ? EditSubAction::decreaseZIndex :
-                                                EditSubAction::increaseZIndex);
+  EditSubActionInfo subActionInfo(aChange < 0 ? EditSubAction::eDecreaseZIndex :
+                                                EditSubAction::eIncreaseZIndex);
   bool cancel, handled;
   // Protect the edit rules object from dying
   RefPtr<TextEditRules> rules(mRules);
   nsresult rv =
     rules->WillDoAction(selection, subActionInfo, &cancel, &handled);
   if (cancel || NS_FAILED(rv)) {
     return rv;
   }

--- a/editor/libeditor/HTMLEditRules.cpp
+++ b/editor/libeditor/HTMLEditRules.cpp
@@ -727,19 +727,19 @@ HTMLEditRules::WillDoAction(Selection* a
     case EditSubAction::eInsertElement: {
       nsresult rv = WillInsert(aCancel);
       if (NS_WARN_IF(rv == NS_ERROR_EDITOR_DESTROYED)) {
         return NS_ERROR_EDITOR_DESTROYED;
       }
       NS_WARNING_ASSERTION(NS_SUCCEEDED(rv), "WillInsert() failed");
       return NS_OK;
     }
-    case EditSubAction::decreaseZIndex:
+    case EditSubAction::eDecreaseZIndex:
       return WillRelativeChangeZIndex(-1, aCancel, aHandled);
-    case EditSubAction::increaseZIndex:
+    case EditSubAction::eIncreaseZIndex:
       return WillRelativeChangeZIndex(1, aCancel, aHandled);
     default:
       return TextEditRules::WillDoAction(&SelectionRef(), aInfo,
                                          aCancel, aHandled);
   }
 }
 
 nsresult