Use C++11 features in core/html

Source/core/html/imports/HTMLImportsController.cpp

 /*
  * Copyright (C) 2013 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 102 matching lines @@
         child->didShareLoader();
         return child;
     }
 
     bool sameOriginRequest = master()->securityOrigin()->canRequest(request.url());
     request.setCrossOriginAccessControl(
         master()->securityOrigin(), sameOriginRequest ? AllowStoredCredentials : DoNotAllowStoredCredentials,
         ClientDidNotRequestCredentials);
     ResourcePtr<RawResource> resource = parent->document()->fetcher()->fetchImport(request);
     if (!resource)
-        return 0;
+        return nullptr;
 
     HTMLImportLoader* loader = createLoader();
     HTMLImportChild* child = createChild(request.url(), loader, parent, client);
     // We set resource after the import tree is built since
     // Resource::addClient() immediately calls back to feed the bytes when the resource is cached.
     loader->startLoading(resource);
     child->didStartLoading();
     return child;
 }
 
@@ skipping 16 matching lines @@
     return m_loaders.last().get();
 }
 
 HTMLImportLoader* HTMLImportsController::loaderFor(const Document& document) const
 {
     for (size_t i = 0; i < m_loaders.size(); ++i) {
         if (m_loaders[i]->document() == &document)
             return m_loaders[i].get();
     }
 
-    return 0;
+    return nullptr;
 }
 
 Document* HTMLImportsController::loaderDocumentAt(size_t i) const
 {
     return loaderAt(i)->document();
 }
 
 void HTMLImportsController::trace(Visitor* visitor)
 {
     visitor->trace(m_root);
     visitor->trace(m_loaders);
     DocumentSupplement::trace(visitor);
 }
 
 } // namespace blink