[LazyParseCSS] Ensure UseCounting has parity with strict parsing

third_party/WebKit/Source/core/css/parser/CSSLazyParsingState.h

 // Copyright 2016 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #ifndef CSSLazyParsingState_h
 #define CSSLazyParsingState_h
 
 #include "core/css/CSSSelectorList.h"
 #include "core/css/StyleSheetContents.h"
 #include "core/css/parser/CSSParserMode.h"
@@ skipping 13 matching lines @@
   CSSLazyParsingState(const CSSParserContext&,
                       Vector<String> escapedStrings,
                       const String& sheetText,
                       StyleSheetContents*);
 
   const CSSParserContext& context();
 
   bool shouldLazilyParseProperties(const CSSSelectorList&,
                                    const CSSParserTokenRange& block);
 
-  DEFINE_INLINE_TRACE() { visitor->trace(m_owningContents); }
+  DECLARE_TRACE();
 
  private:
   CSSParserContext m_context;
   Vector<String> m_escapedStrings;
   // Also referenced on the css resource.
   String m_sheetText;
 
   // Weak to ensure lazy state will never cause the contents to live longer than
   // it should (we DCHECK this fact).
   WeakMember<StyleSheetContents> m_owningContents;
+
+  // Cache the document as a proxy for caching the UseCounter. Grabbing the
+  // UseCounter per every property parse is a bit more expensive.
+  WeakMember<Document> m_document;
 };
 
 }  // namespace blink
 
 #endif  // CSSLazyParsingState_h