Stash ComputedStyles on new HeapHashMap on Document.

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

Index: third_party/WebKit/Source/core/dom/Document.h
diff --git a/third_party/WebKit/Source/core/dom/Document.h b/third_party/WebKit/Source/core/dom/Document.h
index bf6b2ec2e7cc0b3d9532c6c99dcda7366683bb39..31e6fa093898b30380fa398822e1db26da368d18 100644
--- a/third_party/WebKit/Source/core/dom/Document.h
+++ b/third_party/WebKit/Source/core/dom/Document.h
@@ -328,6 +328,9 @@ class CORE_EXPORT Document : public ContainerNode,
   Range* caretRangeFromPoint(int x, int y);
   Element* scrollingElement();
 
+  void addNonAttachedStyle(Element&, RefPtr<ComputedStyle>);
+  ComputedStyle* getNonAttachedStyle(Element&);
+
   String readyState() const;
 
   AtomicString characterSet() const { return Document::encodingName(); }
@@ -1411,6 +1414,8 @@ class CORE_EXPORT Document : public ContainerNode,
   Member<DocumentParser> m_parser;
   Member<ContextFeatures> m_contextFeatures;
 
+  HeapHashMap<Member<Element>, RefPtr<ComputedStyle>> m_nonAttachedStyle;
+
   bool m_wellFormed;
 
   // Document URLs.