Move serializer related files in core/editing/ related files into core/editing/serializers/

Source/core/editing/TextOffset.cpp

-// Copyright 2015 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 "config.h"
-#include "core/editing/TextOffset.h"
-
-#include "core/dom/Text.h"
-
-namespace blink {
-
-TextOffset::TextOffset()
-    : m_offset(0)
-{
-}
-
-TextOffset::TextOffset(PassRefPtrWillBeRawPtr<Text> text, int offset)
-    : m_text(text)
-    , m_offset(offset)
-{
-}
-
-TextOffset::TextOffset(const TextOffset& other)
-    : m_text(other.m_text)
-    , m_offset(other.m_offset)
-{
-}
-
-bool TextOffset::isNull() const
-{
-    return !m_text;
-}
-
-bool TextOffset::isNotNull() const
-{
-    return m_text;
-}
-
-} // namespace blink