LanguageClient: Re-highlight also on empty deltas

This is needed for e.g. ClangdClient, which may need to update even if
the highlighting delta from the server is empty.

Task-number: QTCREATORBUG-26183
Change-Id: I38398c9563fa7a6a1906c5cb57fd1cbcd444cbd9
Reviewed-by: David Schulz <david.schulz@qt.io>

src/plugins/languageclient/client.cpp

@@ -1016,13 +1016,6 @@ void Client::setSemanticTokensHandler(const SemanticTokensHandler &handler)
     m_tokenSupport.setTokensHandler(handler);
 }
 
-#ifdef WITH_TESTS
-void Client::forceHighlightingOnEmptyDelta()
-{
-    m_tokenSupport.forceHighlightingOnEmptyDelta();
-}
-#endif
-
 void Client::setSymbolStringifier(const LanguageServerProtocol::SymbolStringifier &stringifier)
 {
     m_symbolStringifier = stringifier;