Clear document scope dirtiness in import StyleEngine.

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

 /*
  * 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, 2011, 2012 Apple Inc. All
  * rights reserved.
  * Copyright (C) 2008, 2009 Torch Mobile Inc. All rights reserved.
  * (http://www.torchmobile.com/)
  * Copyright (C) 2008, 2009, 2011, 2012 Google Inc. All rights reserved.
@@ skipping 273 matching lines @@
 }
 
 void StyleEngine::MediaQueryAffectingValueChanged() {
   if (GetDocumentStyleSheetCollection().MediaQueryAffectingValueChanged())
     SetNeedsActiveStyleUpdate(GetDocument());
   MediaQueryAffectingValueChanged(active_tree_scopes_);
   if (resolver_)
     resolver_->UpdateMediaType();
 }
 
-void StyleEngine::UpdateStyleSheetsInImport(
+void StyleEngine::UpdateActiveStyleSheetsInImport(
     StyleEngine& master_engine,
     DocumentStyleSheetCollector& parent_collector) {
   DCHECK(!IsMaster());
   HeapVector<Member<StyleSheet>> sheets_for_list;
   ImportedDocumentStyleSheetCollector subcollector(parent_collector,
                                                    sheets_for_list);
   GetDocumentStyleSheetCollection().CollectStyleSheets(master_engine,
                                                        subcollector);
   GetDocumentStyleSheetCollection().SwapSheetsForSheetList(sheets_for_list);
+
+  // all_tree_scopes_dirty_ should only be set on main documents, never html
+  // imports.
+  DCHECK(!all_tree_scopes_dirty_);
+  // Make sure we don't re-collect sheets for style sheet list.
+  document_scope_dirty_ = false;
+  // Dirty tree scopes shadow trees do not affect the main document. Just leave
+  // them dirty here and re-collect when styleSheets is queried on shadow roots
+  // inside html import documents.
+  // tree_scopes_removed_ is irrelevant for html imports as the sheets do not
+  // affect style and removing a shadow tree is reflected directly in
+  // StyleSheetList accessing length or items.
 }
 
 void StyleEngine::UpdateActiveStyleSheetsInShadow(
     TreeScope* tree_scope,
     UnorderedTreeScopeSet& tree_scopes_removed) {
   DCHECK_NE(tree_scope, document_);
   ShadowTreeStyleSheetCollection* collection =
       ToShadowTreeStyleSheetCollection(StyleSheetCollectionFor(*tree_scope));
   DCHECK(collection);
   collection->UpdateActiveStyleSheets(*this);
@@ skipping 882 matching lines @@
 }
 
 DEFINE_TRACE_WRAPPERS(StyleEngine) {
   for (auto sheet : injected_author_style_sheets_) {
     visitor->TraceWrappers(sheet);
   }
   visitor->TraceWrappers(document_style_sheet_collection_);
 }
 
 }  // namespace blink