Implement callback reactions for Custom Elements V1

third_party/WebKit/Source/core/dom/custom/CustomElementReactionTestHelpers.h

 // Copyright 2016 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.
 
 #include "core/dom/custom/CustomElementReaction.h"
 
 #include "core/dom/custom/CustomElementReactionQueue.h"
 #include "platform/heap/Handle.h"
 #include "wtf/Noncopyable.h"
 #include <initializer_list>
@@ skipping 59 matching lines @@
     }
 private:
     Member<CustomElementReactionQueue> m_queue;
     Member<CustomElementReaction> m_reaction;
 };
 
 class TestReaction : public CustomElementReaction {
     WTF_MAKE_NONCOPYABLE(TestReaction);
 public:
     TestReaction(std::initializer_list<Command*> commands)
+        : CustomElementReaction(nullptr)
     {
         // TODO(dominicc): Simply pass the initializer list when
         // HeapVector supports initializer lists like Vector.
         for (auto& command : commands)
             m_commands.append(command);
     }
     ~TestReaction() override = default;
     DEFINE_INLINE_VIRTUAL_TRACE()
     {
         CustomElementReaction::trace(visitor);
         visitor->trace(m_commands);
     }
     void invoke(Element* element) override
     {
         for (auto& command : m_commands)
             command->run(element);
     }
 
 private:
     HeapVector<Member<Command>> m_commands;
 };
 
 } // namespace blink