Add removeAll method to sets and maps and use them

Source/wtf/ListHashSet.h

Index: Source/wtf/ListHashSet.h
diff --git a/Source/wtf/ListHashSet.h b/Source/wtf/ListHashSet.h
index f1624dc359e89877301233181e522c994fe237fd..b08057f5e2312a54f7aa20cc1baf1780728a6d38 100644
--- a/Source/wtf/ListHashSet.h
+++ b/Source/wtf/ListHashSet.h
@@ -156,6 +156,8 @@ namespace WTF {
         void remove(ValuePeekInType);
         void remove(iterator);
         void clear();
+        template<typename Collection>
+        void removeAll(const Collection& other);
 
     private:
         void unlink(Node*);
@@ -838,6 +840,18 @@ namespace WTF {
     }
 
     template<typename T, size_t inlineCapacity, typename U>
+    template<typename Collection>
+    inline void ListHashSet<T, inlineCapacity, U>::removeAll(const Collection& other)
+    {
+        if (other.isEmpty() || isEmpty())
+            return;
+        typedef typename Collection::const_iterator CollectionIterator;
+        CollectionIterator otherEnd(other.end());
+        for (CollectionIterator it(other.begin()); it != otherEnd; ++it)
+            remove(*it);
+    }
+
+    template<typename T, size_t inlineCapacity, typename U>
     void ListHashSet<T, inlineCapacity, U>::unlink(Node* node)
     {
         if (!node->m_prev) {