Add removeAll method to sets and maps and use them

Source/wtf/HashTable.h

 /*
  * Copyright (C) 2005, 2006, 2007, 2008, 2011, 2012 Apple Inc. All rights reserved.
  * Copyright (C) 2008 David Levin <levin@chromium.org>
  *
  * 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
  * version 2 of the License, or (at your option) any later version.
  *
  * This library is distributed in the hope that it will be useful,
@@ skipping 1259 matching lines @@
     {
         return a.m_impl == b.m_impl;
     }
 
     template<typename T, typename U>
     inline bool operator!=(const HashTableIteratorAdapter<T, U>& a, const HashTableConstIteratorAdapter<T, U>& b)
     {
         return a.m_impl != b.m_impl;
     }
 
+    template<typename Collection1, typename Collection2>
+    inline void removeAll(Collection1& collection, const Collection2& toBeRemoved)
+    {
+        if (collection.isEmpty() || toBeRemoved.isEmpty())
+            return;
+        typedef typename Collection2::const_iterator CollectionIterator;
+        CollectionIterator end(toBeRemoved.end());
+        for (CollectionIterator it(toBeRemoved.begin()); it != end; ++it)
+            collection.remove(*it);
+    }
+
 } // namespace WTF
 
 #include "wtf/HashIterators.h"
 
 #endif // WTF_HashTable_h