Storage of ComputedStyle separate from LayoutObject.

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 78872cdcf125b3139e08a8e7752e6eda40cfea34..bb27b73fca10d3fcdcff19c92a68985eb74867b4 100644
--- a/third_party/WebKit/Source/core/dom/NodeComputedStyle.h
+++ b/third_party/WebKit/Source/core/dom/NodeComputedStyle.h
@@ -27,6 +27,7 @@
 
 #include "core/dom/LayoutTreeBuilderTraversal.h"
 #include "core/dom/Node.h"
+#include "core/dom/NodeRareData.h"
 #include "core/dom/shadow/InsertionPoint.h"
 #include "core/html/HTMLOptGroupElement.h"
 #include "core/layout/LayoutObject.h"
@@ -41,14 +42,31 @@ inline const ComputedStyle* Node::computedStyle() const
 
 inline ComputedStyle* Node::mutableComputedStyle() const
 {
-    if (LayoutObject* layoutObject = this->layoutObject())
-        return layoutObject->mutableStyle();
+    if (hasLayoutObject())
+        return layoutObject()->mutableStyle();
     // <option> and <optgroup> can be styled even if they don't get layout objects,
     // so they store their style internally and return it through nonLayoutObjectComputedStyle().
     // We check here explicitly to avoid the virtual call in the common case.
     if (isHTMLOptGroupElement(*this) || isHTMLOptionElement(this))
         return nonLayoutObjectComputedStyle();
-    return 0;
+    if (hasRareData())
+        return rareData()->computedStyle();
+    return m_data.m_computedStyle;
+}
+
+inline void Node::setComputedStyle(PassRefPtr<ComputedStyle> computedStyle)
+{
+    if (hasRareData()) {
+        rareData()->setComputedStyle(computedStyle);
+    } else if (hasLayoutObject()) {
+        m_data.m_layoutObject->setStyleInternal(computedStyle);
+    } else {
+        if (computedStyle)
+            computedStyle->ref();
+        if (m_data.m_computedStyle)
+            m_data.m_computedStyle->deref();
+        m_data.m_computedStyle = computedStyle.get();

[Timothy Loh, 2016/06/02 05:10:32]

Actually here you can write computedStyle.leakRef() and then you don't need to
explicitly call ref() above.

+    }
 }
 
 inline const ComputedStyle* Node::parentComputedStyle() const