Implement lazy block layout prototype behind a runtime flag.

Source/core/rendering/RenderView.cpp

Index: Source/core/rendering/RenderView.cpp
diff --git a/Source/core/rendering/RenderView.cpp b/Source/core/rendering/RenderView.cpp
index e3745f135827a8c6ebde970af38a1a3f2f772e5f..7c84e7cc27c965edb80d02bb504fff97feb79f88 100644
--- a/Source/core/rendering/RenderView.cpp
+++ b/Source/core/rendering/RenderView.cpp
@@ -39,6 +39,7 @@
 #include "core/rendering/RenderLayer.h"
 #include "core/rendering/RenderLayerBacking.h"
 #include "core/rendering/RenderLayerCompositor.h"
+#include "core/rendering/RenderLazyBlock.h"
 #include "core/rendering/RenderNamedFlowThread.h"
 #include "core/rendering/RenderSelectionInfo.h"
 #include "core/rendering/RenderWidget.h"
@@ -63,6 +64,7 @@ RenderView::RenderView(Document* document)
     , m_pageLogicalHeightChanged(false)
     , m_layoutState(0)
     , m_layoutStateDisableCount(0)
+    , m_firstLazyBlock(0)
     , m_renderQuoteHead(0)
     , m_renderCounterCount(0)
 {
@@ -115,6 +117,12 @@ bool RenderView::isChildAllowed(RenderObject* child, RenderStyle*) const
     return child->isBox();
 }
 
+void RenderView::markLazyBlocksForLayout()
+{
+    for (RenderLazyBlock* block = m_firstLazyBlock; block; block = block->next())
+        block->setNeedsLayout(true);
+}
+
 void RenderView::layoutContent(const LayoutState& state)
 {
     UNUSED_PARAM(state);