IDL: Support iterable<>, maplike<> and setlike<> syntax

Source/modules/fetch/Headers.h

 // Copyright 2014 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #ifndef Headers_h
 #define Headers_h
 
 #include "bindings/core/v8/ScriptState.h"
 #include "bindings/core/v8/ScriptWrappable.h"
 #include "modules/fetch/FetchHeaderList.h"
@@ skipping 24 matching lines @@
     Headers* createCopy() const;
 
     // Headers.idl implementation.
     void append(const String& name, const String& value, ExceptionState&);
     void remove(const String& key, ExceptionState&);
     String get(const String& key, ExceptionState&);
     Vector<String> getAll(const String& key, ExceptionState&);
     bool has(const String& key, ExceptionState&);
     void set(const String& key, const String& value, ExceptionState&);
 
-    // Iterable
+    // iterable<ByteString, ByteString>
     Iterator* iterator(ScriptState*, ExceptionState&);
 
     void setGuard(Guard guard) { m_guard = guard; }
     Guard guard() const { return m_guard; }
 
     // These methods should only be called when size() would return 0.
     void fillWith(const Headers*, ExceptionState&);
     void fillWith(const Vector<Vector<String> >&, ExceptionState&);
     void fillWith(const Dictionary&, ExceptionState&);
 
     FetchHeaderList* headerList() const { return m_headerList; }
     void trace(Visitor*);
 
 private:
     Headers();
     // Shares the FetchHeaderList. Called when creating a Request or Response.
     explicit Headers(FetchHeaderList*);
 
     Member<FetchHeaderList> m_headerList;
     Guard m_guard;
 };
 
 } // namespace blink
 
 #endif // Headers_h