Invalidate CustomScrollbars on having window-inactive selector.

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 103 matching lines @@
     void addPendingSheet();
     void removePendingSheet(Node* styleSheetCandidateNode);
 
     bool hasPendingSheets() const { return m_pendingStylesheets > 0; }
     bool haveStylesheetsLoaded() const { return !hasPendingSheets() || m_ignorePendingStylesheets; }
     bool ignoringPendingStylesheets() const { return m_ignorePendingStylesheets; }
 
     unsigned maxDirectAdjacentSelectors() const { return m_maxDirectAdjacentSelectors; }
     bool usesSiblingRules() const { return m_usesSiblingRules; }
     bool usesFirstLineRules() const { return m_usesFirstLineRules; }
+    bool usesWindowInactiveSelector() const { return m_usesWindowInactiveSelector; }
+
     bool usesFirstLetterRules() const { return m_usesFirstLetterRules; }
     void setUsesFirstLetterRules(bool b) { m_usesFirstLetterRules = b; }
     bool usesRemUnits() const { return m_usesRemUnits; }
     void setUsesRemUnit(bool b) { m_usesRemUnits = b; }
 
     void combineCSSFeatureFlags(const RuleFeatureSet&);
     void resetCSSFeatureFlags(const RuleFeatureSet&);
 
     void didRemoveShadowRoot(ShadowRoot*);
     void shadowRootRemovedFromDocument(ShadowRoot*);
@@ skipping 141 matching lines @@
 
     bool m_documentScopeDirty;
     UnorderedTreeScopeSet m_dirtyTreeScopes;
     OrderedTreeScopeSet m_activeTreeScopes;
 
     String m_preferredStylesheetSetName;
     String m_selectedStylesheetSetName;
 
     bool m_usesSiblingRules;
     bool m_usesFirstLineRules;
+    bool m_usesWindowInactiveSelector;
     bool m_usesFirstLetterRules;
     bool m_usesRemUnits;
     unsigned m_maxDirectAdjacentSelectors;
 
     bool m_ignorePendingStylesheets;
     bool m_didCalculateResolver;
     OwnPtrWillBeMember<StyleResolver> m_resolver;
 
     RefPtrWillBeMember<CSSFontSelector> m_fontSelector;
 
     WillBeHeapHashMap<AtomicString, RawPtrWillBeMember<StyleSheetContents> > m_textToSheetCache;
     WillBeHeapHashMap<RawPtrWillBeMember<StyleSheetContents>, AtomicString> m_sheetToTextCache;
 };
 
 }
 
 #endif