Setting the link title may change the preferred set.

third_party/WebKit/Source/core/dom/ProcessingInstruction.cpp

 /*
  * Copyright (C) 2000 Peter Kelly (pmk@post.com)
  * Copyright (C) 2006, 2008, 2009 Apple Inc. All rights reserved.
  *
  * This library is free software; you can redistribute it and/or
  * modify it under the terms of the GNU Library General Public
  * License as published by the Free Software Foundation; either
  * version 2 of the License, or (at your option) any later version.
  *
  * This library is distributed in the hope that it will be useful,
@@ skipping 189 matching lines @@
 
     DCHECK(m_isCSS);
     CSSParserContext parserContext(document(), nullptr, baseURL, charset);
 
     StyleSheetContents* newSheet = StyleSheetContents::create(href, parserContext);
 
     CSSStyleSheet* cssSheet = CSSStyleSheet::create(newSheet, this);
     cssSheet->setDisabled(m_alternate);
     cssSheet->setTitle(m_title);
     if (!m_alternate && !m_title.isEmpty())
-        document().styleEngine().setPreferredStylesheetSetNameIfNotSet(m_title);
+        document().styleEngine().setPreferredStylesheetSetNameIfNotSet(m_title, StyleEngine::DontUpdateActiveSheets);
     cssSheet->setMediaQueries(MediaQuerySet::create(m_media));
 
     m_sheet = cssSheet;
 
     // We don't need the cross-origin security check here because we are
     // getting the sheet text in "strict" mode. This enforces a valid CSS MIME
     // type.
     parseStyleSheet(sheet->sheetText());
 }
 
@@ skipping 76 matching lines @@
 
 DEFINE_TRACE(ProcessingInstruction)
 {
     visitor->trace(m_sheet);
     visitor->trace(m_listenerForXSLT);
     CharacterData::trace(visitor);
     ResourceOwner<StyleSheetResource>::trace(visitor);
 }
 
 } // namespace blink