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diff --git a/Source/WTF/wtf/IndexedContainerIterator.h b/Source/WTF/wtf/IndexedContainerIterator.h
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+/*
+ * Copyright (C) 2015-2016 Apple Inc. All rights reserved.
+ *
+ * Redistribution and use in source and binary forms, with or without
+ * modification, are permitted provided that the following conditions
+ * are met:
+ * 1. Redistributions of source code must retain the above copyright
+ *    notice, this list of conditions and the following disclaimer.
+ * 2. Redistributions in binary form must reproduce the above copyright
+ *    notice, this list of conditions and the following disclaimer in the
+ *    documentation and/or other materials provided with the distribution.
+ *
+ * THIS SOFTWARE IS PROVIDED BY APPLE INC. ``AS IS'' AND ANY
+ * EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
+ * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
+ * PURPOSE ARE DISCLAIMED.  IN NO EVENT SHALL APPLE INC. OR
+ * CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL,
+ * EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO,
+ * PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR
+ * PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY
+ * OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
+ * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
+ * OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
+ */
+
+#pragma once
+
+#include <type_traits>
+
+namespace WTF {
+
+template<class Container>
+class IndexedContainerIterator {
+public:
+    IndexedContainerIterator()
+        : m_container(nullptr)
+        , m_index(0)
+    {
+    }
+
+    IndexedContainerIterator(const Container& container, unsigned index)
+        : m_container(&container)
+        , m_index(findNext(index))
+    {
+    }
+
+    auto operator*() -> typename std::result_of<decltype(&Container::at)(const Container, unsigned)>::type
+    {
+        return m_container->at(m_index);
+    }
+
+    IndexedContainerIterator& operator++()
+    {
+        m_index = findNext(m_index + 1);
+        return *this;
+    }
+
+    bool operator==(const IndexedContainerIterator& other) const
+    {
+        ASSERT(m_container == other.m_container);
+        return m_index == other.m_index;
+    }
+
+    bool operator!=(const IndexedContainerIterator& other) const
+    {
+        return !(*this == other);
+    }
+
+private:
+    unsigned findNext(unsigned index)
+    {
+        while (index < m_container->size() && !m_container->at(index))
+            index++;
+        return index;
+    }
+
+    const Container* m_container;
+    unsigned m_index;
+};
+
+} // namespace WTF