Avoid synchronous stylesheet update on html import loaded.

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)
@@ skipping 99 matching lines @@
   void WatchedSelectorsChanged();
   void InitialViewportChanged();
   void ViewportRulesChanged();
   void HtmlImportAddedOrRemoved();
 
   void InjectAuthorSheet(StyleSheetContents* author_sheet);
   CSSStyleSheet& EnsureInspectorStyleSheet();
   RuleSet* WatchedSelectorsRuleSet() {
     return global_rule_set_.WatchedSelectorsRuleSet();
   }
+  bool HasStyleSheets() const {
+    return GetDocumentStyleSheetCollection().HasStyleSheets();
+  }
 
   RuleSet* RuleSetForSheet(CSSStyleSheet&);
   void MediaQueryAffectingValueChanged();
   void UpdateStyleSheetsInImport(StyleEngine& master_engine,
                                  DocumentStyleSheetCollector& parent_collector);
   void UpdateActiveStyle();
   void MarkAllTreeScopesDirty() { all_tree_scopes_dirty_ = true; }
 
   String PreferredStylesheetSetName() const {
     return preferred_stylesheet_set_name_;
@@ skipping 256 matching lines @@
 
   std::unique_ptr<StyleResolverStats> style_resolver_stats_;
   unsigned style_for_element_count_ = 0;
 
   friend class StyleEngineTest;
 };
 
 }  // namespace blink
 
 #endif