Bug 1448780 - Get rid of nsIEditor.numberOfUndoItems and nsIEditor.numberOfRedoItems r=m_kato

nsIEditor.numberOfUndoItems and nsIEditor.numberOfRedoItems are shortcut
property for nsITransactionManager.numberOfUndoItems and
nsITransactionManager.numberOfRedoItems of the editor.  However, anybody
uses nsITransactionManager directly.  So, we can get rid of them.

MozReview-Commit-ID: 70J0bsxDNCC

--HG--
extra : rebase_source : fd0847687fe595b257b0256a5f1faa5f2df5f972

editor/libeditor/EditorBase.cpp

@@ -827,22 +827,6 @@ EditorBase::EnableUndo(bool aEnable)
   return NS_OK;
 }
 
-NS_IMETHODIMP
-EditorBase::GetNumberOfUndoItems(int32_t* aNumItems)
-{
-  *aNumItems = static_cast<int32_t>(NumberOfUndoItems());
-  MOZ_ASSERT(*aNumItems >= 0);
-  return NS_OK;
-}
-
-NS_IMETHODIMP
-EditorBase::GetNumberOfRedoItems(int32_t* aNumItems)
-{
-  *aNumItems = static_cast<int32_t>(NumberOfRedoItems());
-  MOZ_ASSERT(*aNumItems >= 0);
-  return NS_OK;
-}
-
 NS_IMETHODIMP
 EditorBase::GetTransactionManager(nsITransactionManager** aTransactionManager)
 {

editor/nsIEditor.idl

@@ -169,16 +169,6 @@ interface nsIEditor  : nsISupports
     */
   void enableUndo(in boolean enable);
 
-  /**
-   * The number of items on the undo stack.
-   */
-  readonly attribute long numberOfUndoItems;
-
-  /**
-   * The number of items on the redo stack.
-   */
-  readonly attribute long numberOfRedoItems;
-
   /** undo reverses the effects of the last Do operation,
     * if Undo is enabled in the editor.
     * It is provided here so clients need no knowledge of whether