LanguageClient: directly update document highlights on changes

If the document highlights are requested after a timeout the document
might have changed again inbetween leading to another document change
notification that gets send to the server.

Change-Id: I476e833c55e1bed96c9bd49ee2f17915ee3536a2
Reviewed-by: Christian Kandeler <christian.kandeler@qt.io>

src/plugins/languageclient/client.cpp

@@ -1195,7 +1195,7 @@ void Client::sendPostponedDocumentUpdates()
         emit documentUpdated(update.document);
 
         if (currentWidget && currentWidget->textDocument() == update.document)
-            cursorPositionChanged(currentWidget);
+            requestDocumentHighlights(currentWidget);
 
         m_tokentSupport.updateSemanticTokens(update.document);
     }