Avoid always style recalc when removing stylesheets.

Source/core/html/HTMLStyleElement.cpp

 /*
  * Copyright (C) 1999 Lars Knoll (knoll@kde.org)
  *           (C) 1999 Antti Koivisto (koivisto@kde.org)
  *           (C) 2001 Dirk Mueller (mueller@kde.org)
  * Copyright (C) 2003, 2010 Apple Inc. All rights reserved.
  *           (C) 2007 Rob Buis (buis@kde.org)
  *
  * This library is free software; you can redistribute it and/or
  * modify it under the terms of the GNU Library General Public
  * License as published by the Free Software Foundation; either
@@ skipping 106 matching lines @@
 
     document().styleEngine()->removeStyleSheetCandidateNode(this, parentNode());
     unregisterWithScopingNode(parentNode());
 
     // As any <style> in a shadow tree is treated as "scoped",
     // need to add the <style> to its shadow root.
     if (isInShadowTree())
         registerWithScopingNode(false);
 
     document().styleEngine()->addStyleSheetCandidateNode(this, false);
+    // FIXME: currently need to use FullStyleUpdate here.
+    // Because ShadowTreeStyleSheetCollection doesn't know old scoping node.
+    // So setNeedsStyleRecalc for old scoping node is not invoked.
     document().modifiedStyleSheet(sheet());
 }
 
 void HTMLStyleElement::finishParsingChildren()
 {
     StyleElement::finishParsingChildren(this);
     HTMLElement::finishParsingChildren();
 }
 
 void HTMLStyleElement::registerWithScopingNode(bool scoped)
@@ skipping 147 matching lines @@
     return m_sheet->disabled();
 }
 
 void HTMLStyleElement::setDisabled(bool setDisabled)
 {
     if (CSSStyleSheet* styleSheet = sheet())
         styleSheet->setDisabled(setDisabled);
 }
 
 }