Set ComputedStyle on Node and use that in buildOwnLayout()

third_party/WebKit/Source/core/dom/NodeComputedStyle.h

Index: third_party/WebKit/Source/core/dom/NodeComputedStyle.h
diff --git a/third_party/WebKit/Source/core/dom/NodeComputedStyle.h b/third_party/WebKit/Source/core/dom/NodeComputedStyle.h
index d7345264df9b5a75a8206a69643b3dba166c56d9..27bcd0f912a68db1220ced8a11001da383bad1ac 100644
--- a/third_party/WebKit/Source/core/dom/NodeComputedStyle.h
+++ b/third_party/WebKit/Source/core/dom/NodeComputedStyle.h
@@ -59,6 +59,23 @@ inline ComputedStyle* Node::mutableComputedStyle() const
     return m_data.m_computedStyle;
 }
 
+inline void Node::setComputedStyle(PassRefPtr<ComputedStyle> computedStyle)
+{
+    // Note that if the DataUnion is a LayoutObject it is the old LayoutObject which will be detached in reattachLayoutTree.
+    // We don't want to associated the new ComputedStyle with the old LayoutObject. So we don't do anything at this stage.
+    if (hasRareData()) {
+        // If the DataUnion is an ElementRareData - set the ComputedStyle on that ElementRareData.
+        NodeRareData* rareData = this->rareData();
+        if (rareData->isElementRareData())
+            static_cast<ElementRareData*>(rareData)->setComputedStyle(computedStyle);
+    } else {
+        // If the DataUnion is a ComputedStyle - make it point to the new ComputedStyle passed in.
+        if (m_data.m_computedStyle)
+            m_data.m_computedStyle->deref();
+        m_data.m_computedStyle = computedStyle.leakRef();
+    }
+}
+
 inline const ComputedStyle* Node::parentComputedStyle() const
 {
     if (isSlotOrActiveInsertionPoint())