Editor: Ensure cursor is visible before completion popup

Task-number: QTCREATORBUG-6843

Change-Id: I4f4108bdf37cb1451d998e226e97b3ee7fbc3a33
Reviewed-by: Fawzi Mohamed <fawzi.mohamed@nokia.com>

src/plugins/texteditor/basetexteditor.cpp

@@ -6454,6 +6454,7 @@ void BaseTextEditorWidget::invokeAssist(AssistKind kind, IAssistProvider *provid
 {
     if (overwriteMode())
         return;
+    ensureCursorVisible();
     d->m_codeAssistant->invoke(kind, provider);
 }