Add a missing null check to LinkStyle::process()

Source/core/html/HTMLLinkElement.cpp

 /*
  * Copyright (C) 1999 Lars Knoll (knoll@kde.org)
  *           (C) 1999 Antti Koivisto (koivisto@kde.org)
  *           (C) 2001 Dirk Mueller (mueller@kde.org)
  * Copyright (C) 2003, 2006, 2007, 2008, 2009, 2010 Apple Inc. All rights reserved.
  * Copyright (C) 2009 Rob Buis (rwlbuis@gmail.com)
  * Copyright (C) 2011 Google 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
@@ skipping 609 matching lines @@
     String type = m_owner->typeValue().lower();
     LinkRequestBuilder builder(m_owner);
 
     if (m_owner->relAttribute().iconType() != InvalidIcon && builder.url().isValid() && !builder.url().isEmpty()) {
         if (!m_owner->shouldLoadLink())
             return;
         if (!document().securityOrigin()->canDisplay(builder.url()))
             return;
         if (!document().contentSecurityPolicy()->allowImageFromSource(builder.url()))
             return;
-        if (document().frame())
+        if (document().frame() && document().frame()->loader().client())
             document().frame()->loader().client()->dispatchDidChangeIcons(m_owner->relAttribute().iconType());
     }
 
     if (!m_owner->loadLink(type, builder.url()))
         return;
 
     if ((m_disabledState != Disabled) && m_owner->relAttribute().isStyleSheet()
         && shouldLoadResource() && builder.url().isValid()) {
 
         if (resource()) {
@@ skipping 51 matching lines @@
 void LinkStyle::ownerRemoved()
 {
     if (m_sheet)
         clearSheet();
 
     if (styleSheetIsLoading())
         removePendingSheet(RemovePendingSheetNotifyLater);
 }
 
 } // namespace WebCore