Bug 1484119 - part 1: Create HTMLEditor::DeleteTableCellWithTransacti…

…on() for internal use of nsITableEditor::DeleteTableCell() r=m_kato

nsITableEditor::DeleteTableCell() is an XPCOM method but used internally.
So, HTMLEditor should implement it with non-virtual method and use it
internally.

Differential Revision: https://phabricator.services.mozilla.com/D6176

editor/libeditor/HTMLEditor.h

@@ -1630,6 +1630,22 @@ class HTMLEditor final : public TextEditor
   nsresult
   DeleteTableRowWithTransaction(Element& aTableElement, int32_t aRowIndex);
 
+  /**
+   * DeleteTableCellWithTransaction() removes table cell elements.  If two or
+   * more cell elements are selected, this removes all selected cell elements.
+   * Otherwise, this removes some cell elements starting from selected cell
+   * element or a cell containing first selection range.  When this removes
+   * last cell element in <tr> or <table>, this removes the <tr> or the
+   * <table> too.  Note that when removing a cell causes number of its row
+   * becomes less than the others, this method does NOT fill the place with
+   * rowspan nor colspan.  This does not return error even if selection is not
+   * in cell element, just does nothing.
+   *
+   * @param aNumberOfCellsToDelete  Number of cells to remove.  This is ignored
+   *                                if 2 or more cells are selected.
+   */
+  nsresult DeleteTableCellWithTransaction(int32_t aNumberOfCellsToDelete);
+
   /**
    * DeleteAllChildrenWithTransaction() removes all children of aElement from
    * the tree.

editor/libeditor/HTMLEditorDataTransfer.cpp

@@ -321,11 +321,14 @@ HTMLEditor::DoInsertHTMLWithContext(const nsAString& aInputString,
     // Delete whole cells: we will replace with new table content.
 
     // Braces for artificial block to scope AutoSelectionRestorer.
-    // Save current selection since DeleteTableCell() perturbs it.
+    // Save current selection since DeleteTableCellWithTransaction() perturbs
+    // it.
     {
       AutoSelectionRestorer selectionRestorer(selection, this);
-      rv = DeleteTableCell(1);
-      NS_ENSURE_SUCCESS(rv, rv);
+      rv = DeleteTableCellWithTransaction(1);
+      if (NS_WARN_IF(NS_FAILED(rv))) {
+        return rv;
+      }
     }
     // collapse selection to beginning of deleted table content
     selection->CollapseToStart(IgnoreErrors());