Add removeAll method to sets and maps and use them

Source/web/AssociatedURLLoader.cpp

Index: Source/web/AssociatedURLLoader.cpp
diff --git a/Source/web/AssociatedURLLoader.cpp b/Source/web/AssociatedURLLoader.cpp
index c7f0a29756ec7cab9cbeb587c0eee24ec09f6b25..7b4079e1e90cfc5252ad83230734c235a62025cd 100644
--- a/Source/web/AssociatedURLLoader.cpp
+++ b/Source/web/AssociatedURLLoader.cpp
@@ -111,9 +111,7 @@ const HTTPHeaderSet& HTTPResponseHeaderValidator::blockedHeaders()
         m_exposedHeaders.remove("set-cookie2");
         // Block Access-Control-Expose-Header itself. It could be exposed later.
         m_blockedHeaders.add("access-control-expose-headers");
-        HTTPHeaderSet::const_iterator end = m_exposedHeaders.end();
-        for (HTTPHeaderSet::const_iterator it = m_exposedHeaders.begin(); it != end; ++it)
-            m_blockedHeaders.remove(*it);
+        m_blockedHeaders.removeAll(m_exposedHeaders);
     }
 
     return m_blockedHeaders;