Consider "mixed content XHR" as mixed script instead of mixed display.

Source/core/loader/DocumentThreadableLoader.cpp

 /*
  * Copyright (C) 2011, 2012 Google Inc. All rights reserved.
  *
  * Redistribution and use in source and binary forms, with or without
  * modification, are permitted provided that the following conditions are
  * met:
  *
  *     * Redistributions of source code must retain the above copyright
  * notice, this list of conditions and the following disclaimer.
  *     * Redistributions in binary form must reproduce the above
@@ skipping 376 matching lines @@
         return;
     }
 
     // FIXME: ThreadableLoaderOptions.sniffContent is not supported for synchronous requests.
     Vector<char> data;
     ResourceError error;
     ResourceResponse response;
     unsigned long identifier = std::numeric_limits<unsigned long>::max();
     if (Frame* frame = m_document->frame()) {
         Frame* top = frame->tree()->top();
-        if (!top->loader()->mixedContentChecker()->canDisplayInsecureContent(top->document()->securityOrigin(), requestURL)) {
+        if (!top->loader()->mixedContentChecker()->canRunInsecureContent(top->document()->securityOrigin(), requestURL)) {
             m_client->didFail(error);
             return;
         }
         identifier = frame->loader()->loadResourceSynchronously(request, m_options.allowCredentials, error, response, data);
     }
 
     InspectorInstrumentation::documentThreadableLoaderStartedLoadingForClient(m_document, identifier, m_client);
 
     // No exception for file:/// resources, see <rdar://problem/4962298>.
     // Also, if we have an HTTP response, then it wasn't a network error in fact.
@@ skipping 26 matching lines @@
 
     return m_sameOriginRequest && securityOrigin()->canRequest(url);
 }
 
 SecurityOrigin* DocumentThreadableLoader::securityOrigin() const
 {
     return m_options.securityOrigin ? m_options.securityOrigin.get() : m_document->securityOrigin();
 }
 
 } // namespace WebCore