Remove willRequestResource callback, it is unused outside of tests.

Source/core/fetch/ResourceFetcher.cpp

 /*
     Copyright (C) 1998 Lars Knoll (knoll@mpi-hd.mpg.de)
     Copyright (C) 2001 Dirk Mueller (mueller@kde.org)
     Copyright (C) 2002 Waldo Bastian (bastian@kde.org)
     Copyright (C) 2004, 2005, 2006, 2007, 2008, 2009, 2010, 2011 Apple Inc. All rights reserved.
     Copyright (C) 2009 Torch Mobile Inc. http://www.torchmobile.com/
 
     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
@@ skipping 337 matching lines @@
 
     // If only the fragment identifiers differ, it is the same resource.
     url = MemoryCache::removeFragmentIdentifierIfNeeded(url);
 
     if (!url.isValid())
         return nullptr;
 
     if (!context().canRequest(factory.type(), request.resourceRequest(), url, request.options(), request.forPreload(), request.originRestriction()))
         return nullptr;
 
-    context().dispatchWillRequestResource(&request);
-
     if (!request.forPreload()) {
         V8DOMActivityLogger* activityLogger = nullptr;
         if (request.options().initiatorInfo.name == FetchInitiatorTypeNames::xmlhttprequest)
             activityLogger = V8DOMActivityLogger::currentActivityLogger();
         else
             activityLogger = V8DOMActivityLogger::currentActivityLoggerIfIsolatedWorld();
 
         if (activityLogger) {
             Vector<String> argv;
             argv.append(Resource::resourceTypeToString(factory.type(), request.options().initiatorInfo));
@@ skipping 777 matching lines @@
     visitor->trace(m_archiveResourceCollection);
     visitor->trace(m_loaders);
     visitor->trace(m_nonBlockingLoaders);
 #if ENABLE(OILPAN)
     visitor->trace(m_preloads);
     visitor->trace(m_resourceTimingInfoMap);
 #endif
 }
 
 }