Add support for printing multicol containers, and enable it.

third_party/WebKit/Source/core/layout/ViewFragmentationContext.h

+// 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.
+
+#ifndef ViewFragmentationContext_h
+#define ViewFragmentationContext_h
+
+#include "core/layout/FragmentationContext.h"
+
+namespace blink {
+
+class LayoutView;
+
+class ViewFragmentationContext final : public FragmentationContext {
+public:
+    ViewFragmentationContext(LayoutView& view) : m_view(view) { }
+    bool isFragmentainerLogicalHeightKnown() final;
+    LayoutUnit fragmentainerLogicalHeightAt(LayoutUnit blockOffset) final;
+    LayoutUnit remainingLogicalHeightAt(LayoutUnit blockOffset) final;
+
+private:
+    LayoutView& m_view;
+};
+
+} // namespace blink
+
+#endif // ViewFragmentationContext_h