IDL: Add PropertyBag class

Source/core/testing/DictionaryTest.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 DictionaryTest_h
 #define DictionaryTest_h
 
 #include "bindings/core/v8/Nullable.h"
 #include "bindings/core/v8/ScriptWrappable.h"
+#include "core/dom/Element.h"
 #include "platform/heap/Handle.h"
 #include "wtf/text/WTFString.h"
 
 namespace blink {
 
 class InternalDictionary;
 
 class DictionaryTest : public GarbageCollectedFinalized<DictionaryTest>, public ScriptWrappable {
 public:
     static DictionaryTest* create()
     {
         return new DictionaryTest();
     }
     virtual ~DictionaryTest();
 
     // Stores all members into corresponding fields
     void set(const InternalDictionary*);
     // Creates a TestDictionary instnace from fields and returns it
     InternalDictionary* get();
 
     void trace(Visitor*);
 
 private:
     DictionaryTest();
 
     void reset();
 
     // The reason to use Nullable<T> is convenience; we use Nullable<T> here to
-    // record whether the member field is set or not. |stringMember| isn't
-    // wrapped with Nullable because |stringMember| has a non-null default value
-    Nullable<unsigned> m_longMember;
+    // record whether the member field is set or not. Some members are not
+    // wrapped with Nullable because:
+    //  - |longMemberWithDefault| has a non-null default value
+    //  - String and PtrTypes can express whether they are null
+    Nullable<int> m_longMember;
+    int m_longMemberWithDefault;
+    Nullable<int> m_longOrNullMember;
+    Nullable<int> m_longOrNullMemberWithDefault;
+    Nullable<bool> m_booleanMember;
+    Nullable<double> m_doubleMember;
     String m_stringMember;
-    Nullable<bool> m_booleanOrNullMember;
-    Nullable<double> m_doubleOrNullMember;
+    String m_stringMemberWithDefault;
     Nullable<Vector<String> > m_stringSequenceMember;
+    Nullable<Vector<String> > m_stringSequenceOrNullMember;
+    RefPtrWillBeMember<Element> m_elementMember;
+    RefPtrWillBeMember<Element> m_elementOrNullMember;
 };
 
 } // namespace blink
 
 #endif // DictionaryTest_h