[New Multicolumn] Support for paged overflow.

Source/core/rendering/RenderPagedFlowThread.cpp

Index: Source/core/rendering/RenderPagedFlowThread.cpp
diff --git a/Source/core/rendering/RenderPagedFlowThread.cpp b/Source/core/rendering/RenderPagedFlowThread.cpp
new file mode 100644
index 0000000000000000000000000000000000000000..08fbb51abd82b802b24151b3cce26fd243733e29
--- /dev/null
+++ b/Source/core/rendering/RenderPagedFlowThread.cpp
@@ -0,0 +1,42 @@
+// 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.
+
+#include "config.h"
+#include "core/rendering/RenderPagedFlowThread.h"
+
+namespace WebCore {
+
+RenderPagedFlowThread* RenderPagedFlowThread::createAnonymous(Document& document, RenderStyle* parentStyle)
+{
+    RenderPagedFlowThread* renderer = new RenderPagedFlowThread();
+    renderer->setDocumentForAnonymous(&document);
+    renderer->setStyle(RenderStyle::createAnonymousStyleWithDisplay(parentStyle, BLOCK));
+    return renderer;
+}
+
+const char* RenderPagedFlowThread::renderName() const
+{
+    return "RenderPagedFlowThread";
+}
+
+bool RenderPagedFlowThread::needsNewWidth() const
+{
+    return progressionIsInline() != pagedBlockFlow()->style()->hasInlinePaginationAxis();
+}
+
+void RenderPagedFlowThread::updateLogicalWidth()
+{
+    // As long as we inherit from RenderMultiColumnFlowThread, we need to bypass its implementation
+    // here. We're not split into columns, so the flow thread width will just be whatever is
+    // available in the containing block.
+    RenderFlowThread::updateLogicalWidth();
+}
+
+void RenderPagedFlowThread::layout()
+{
+    setProgressionIsInline(pagedBlockFlow()->style()->hasInlinePaginationAxis());
+    RenderMultiColumnFlowThread::layout();
+}
+
+} // namespace WebCore