Avoid the hash table StyleInvalidator::clearInvalidation in Node::detach when possible

Source/core/css/invalidation/StyleInvalidator.cpp

 
 // Copyright 2014 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #include "config.h"
 
 #include "core/css/invalidation/StyleInvalidator.h"
 
 #include "core/dom/Document.h"
@@ skipping 23 matching lines @@
 StyleInvalidator::InvalidationList& StyleInvalidator::ensurePendingInvalidationList(Element& element)
 {
     PendingInvalidationMap::AddResult addResult = m_pendingInvalidationMap.add(&element, nullptr);
     if (addResult.isNewEntry)
         addResult.storedValue->value = adoptPtr(new InvalidationList);
     return *addResult.storedValue->value;
 }
 
 void StyleInvalidator::clearInvalidation(Node& node)
 {
+    if (node.isElementNode() && node.needsStyleInvalidation())
+        m_pendingInvalidationMap.remove(toElement(&node));
     node.clearChildNeedsStyleInvalidation();
     node.clearNeedsStyleInvalidation();
-    if (node.isElementNode())
-        m_pendingInvalidationMap.remove(toElement(&node));
 }
 
 void StyleInvalidator::clearPendingInvalidations()
 {
     m_pendingInvalidationMap.clear();
 }
 
 StyleInvalidator::StyleInvalidator()
 { }
 
@@ skipping 90 matching lines @@
         }
     }
 
     element.clearChildNeedsStyleInvalidation();
     element.clearNeedsStyleInvalidation();
 
     return thisElementNeedsStyleRecalc;
 }
 
 } // namespace WebCore