Add removeAll method to sets and maps and use them

Source/wtf/HashMap.h

Index: Source/wtf/HashMap.h
diff --git a/Source/wtf/HashMap.h b/Source/wtf/HashMap.h
index dd15c3d4f308ad1440dd113f8f66fcfa3ed81a32..035c88b54da64b2c23b3801b040c30bc9b2e4216 100644
--- a/Source/wtf/HashMap.h
+++ b/Source/wtf/HashMap.h
@@ -126,6 +126,8 @@ namespace WTF {
         void remove(KeyPeekInType);
         void remove(iterator);
         void clear();
+        template<typename Collection>
+        void removeAll(const Collection& other);
 
         MappedPassOutType take(KeyPeekInType); // efficient combination of get with remove
 
@@ -412,6 +414,18 @@ namespace WTF {
     }
 
     template<typename T, typename U, typename V, typename W, typename X, typename Y>
+    template<typename Collection>
+    inline void HashMap<T, U, V, W, X, Y>::removeAll(const Collection& other)

[Mikhail, 2014/04/25 11:02:26]

I'm a bit concerned that this code is repeated at every container, can we
introduce a generic free function (for instance in HashTable.h) that would be
invoked from each of 'removeAll' methods?

[Erik Corry, 2014/04/25 12:00:31]

Done.

+    {
+        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, typename U, typename V, typename W, typename X, typename Y>
     typename HashMap<T, U, V, W, X, Y>::MappedPassOutType
     HashMap<T, U, V, W, X, Y>::take(KeyPeekInType key)
     {