Add removeAll method to sets and maps and use them

Source/core/fetch/ResourceFetcher.cpp

Index: Source/core/fetch/ResourceFetcher.cpp
diff --git a/Source/core/fetch/ResourceFetcher.cpp b/Source/core/fetch/ResourceFetcher.cpp
index db8d7e4c664c98d07df12ada8209be7c65b3795a..954ba6dbda5e6d3d4f7d8ce59da7e5901cf9692d 100644
--- a/Source/core/fetch/ResourceFetcher.cpp
+++ b/Source/core/fetch/ResourceFetcher.cpp
@@ -1111,8 +1111,7 @@ void ResourceFetcher::garbageCollectDocumentResources()
             resourcesToDelete.append(it->key);
     }
 
-    for (StringVector::const_iterator it = resourcesToDelete.begin(); it != resourcesToDelete.end(); ++it)
-        m_documentResources.remove(*it);
+    m_documentResources.removeAll(resourcesToDelete);
 }
 
 void ResourceFetcher::notifyLoadedFromMemoryCache(Resource* resource)