[Oilpan] Prepare full definition of classes before using Member

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

 /*
  * Copyright (C) 1999 Lars Knoll (knoll@kde.org)
  *           (C) 1999 Antti Koivisto (koivisto@kde.org)
  *           (C) 2001 Dirk Mueller (mueller@kde.org)
  *           (C) 2006 Alexey Proskuryakov (ap@webkit.org)
  * Copyright (C) 2004, 2005, 2006, 2007, 2008, 2009, 2010, 2012 Apple Inc. All rights reserved.
  * Copyright (C) 2008, 2009 Torch Mobile Inc. All rights reserved. (http://www.torchmobile.com/)
  * Copyright (C) 2010 Nokia Corporation and/or its subsidiary(-ies)
  * Copyright (C) 2011 Google Inc. All rights reserved.
  *
@@ skipping 133 matching lines @@
         }
         return *m_resolver.get();
     }
 
     bool hasResolver() const { return m_resolver.get(); }
     void clearResolver();
     void clearMasterResolver();
 
     StyleInvalidator& styleInvalidator() { return m_styleInvalidator; }
 
-    CSSFontSelector* fontSelector() { return m_fontSelector.get(); }
+    CSSFontSelector* fontSelector() const;
     void setFontSelector(PassRefPtrWillBeRawPtr<CSSFontSelector>);
 
     void removeFontFaceRules(const WillBeHeapVector<RawPtrWillBeMember<const StyleRuleFontFace>>&);
     void clearFontCache();
     // updateGenericFontFamilySettings is used from WebSettingsImpl.
     void updateGenericFontFamilySettings();
 
     void didDetach();
     bool shouldClearResolver() const;
     void resolverChanged(StyleResolverUpdateMode);
@@ skipping 90 matching lines @@
 
     RefPtrWillBeMember<CSSFontSelector> m_fontSelector;
 
     WillBeHeapHashMap<AtomicString, RawPtrWillBeMember<StyleSheetContents>> m_textToSheetCache;
     WillBeHeapHashMap<RawPtrWillBeMember<StyleSheetContents>, AtomicString> m_sheetToTextCache;
 };
 
 }
 
 #endif