TextEditor: Remove some *Widget::createEditor implementation

This removes the ones that were not to be used anymore.
The fallback in the base class is left in for now.

Change-Id: I5e7ab16497a83eff9b11deb9e1feb390757eac0e
Reviewed-by: Christian Stenger <christian.stenger@digia.com>

src/plugins/texteditor/snippets/snippeteditor.cpp

@@ -73,9 +73,4 @@ void SnippetEditorWidget::focusOutEvent(QFocusEvent *event)
     BaseTextEditorWidget::focusOutEvent(event);
 }
 
-BaseTextEditor *SnippetEditorWidget::createEditor()
-{
-    QTC_ASSERT("should not happen anymore" && false, return 0);
-}
-
 } // namespace