Move LayoutObject to satellite NodeLayoutData that hangs from a Node.

third_party/WebKit/Source/core/dom/Node.cpp

Index: third_party/WebKit/Source/core/dom/Node.cpp
diff --git a/third_party/WebKit/Source/core/dom/Node.cpp b/third_party/WebKit/Source/core/dom/Node.cpp
index e7d6f098551ae1870c005465e4180553085f1d3f..95a9f0888257a21e1c6359fb362f4a31dffc0a79 100644
--- a/third_party/WebKit/Source/core/dom/Node.cpp
+++ b/third_party/WebKit/Source/core/dom/Node.cpp
@@ -298,6 +298,8 @@ Node::~Node() {
   // With Oilpan, the rare data finalizer also asserts for
   // this condition (we cannot directly access it here.)
   CHECK(HasRareData() || !GetLayoutObject());
+  if (!HasRareData() && !data_.node_layout_data_->IsSharedEmptyData())
+    delete data_.node_layout_data_;
   InstanceCounters::DecrementNodeCounter();
 }
 
@@ -311,9 +313,9 @@ NodeRareData& Node::EnsureRareData() {
     return *RareData();
 
   if (IsElementNode())
-    data_.rare_data_ = ElementRareData::Create(data_.layout_object_);
+    data_.rare_data_ = ElementRareData::Create(data_.node_layout_data_);
   else
-    data_.rare_data_ = NodeRareData::Create(data_.layout_object_);
+    data_.rare_data_ = NodeRareData::Create(data_.node_layout_data_);
 
   DCHECK(data_.rare_data_);
   SetFlag(kHasRareDataFlag);
@@ -589,6 +591,20 @@ LayoutBox* Node::GetLayoutBox() const {
                                                  : nullptr;
 }
 
+void Node::SetLayoutObject(LayoutObject* layout_object) {

[esprehn, 2017/04/13 18:41:08]

This allocates a NodeLayoutData when setting a nullptr for layout_object, but
that's probably not what we want.

You could do something like:

NodeLayoutData* data = HasRareData() ? data_.rare_data_->GetNodeLayoutData() :
data_.node_layout_data_;
if (!data->IsSharedEmptyData()) {
  data->SetLayoutObject(layout_object);
  return;
}
if (!layout_object)
  return;
data = new NodeLayoutData(layout_object);
if (HasRareData()) {
  data_.rare_data_->SetNodeLayoutData(data);
} else {
  data_.node_layout_data_ = data;
}

[nainar, 2017/04/13 20:21:03]

Done. Also commented inline. 

+  if (HasRareData()) {
+    if (data_.rare_data_->GetNodeLayoutData()->IsSharedEmptyData())
+      data_.rare_data_->SetNodeLayoutData(new NodeLayoutData(layout_object));
+    else
+      data_.rare_data_->GetNodeLayoutData()->SetLayoutObject(layout_object);
+  } else {
+    if (data_.node_layout_data_->IsSharedEmptyData())
+      data_.node_layout_data_ = new NodeLayoutData(layout_object);
+    else
+      data_.node_layout_data_->SetLayoutObject(layout_object);
+  }
+}
+
 LayoutBoxModelObject* Node::GetLayoutBoxModelObject() const {
   LayoutObject* layout_object = this->GetLayoutObject();
   return layout_object && layout_object->IsBoxModelObject()