Simplify the SelectorQuery constructor and reuse CSSSelectorList::length().

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

 /*
  * Copyright (C) 2011, 2013 Apple Inc. All rights reserved.
  * Copyright (C) 2014 Samsung Electronics. All rights reserved.
  *
  * Redistribution and use in source and binary forms, with or without
  * modification, are permitted provided that the following conditions
  * are met:
  *
  * 1.  Redistributions of source code must retain the above copyright
  *     notice, this list of conditions and the following disclaimer.
@@ skipping 113 matching lines @@
 
   for (const auto& selector : m_selectors) {
     if (selectorMatches(*selector, targetElement, targetElement))
       return true;
   }
 
   return false;
 }
 
 Element* SelectorQuery::closest(Element& targetElement) const {
-  if (m_selectors.size() == 0)
+  if (m_selectors.isEmpty())
     return nullptr;
   if (m_needsUpdatedDistribution)
     targetElement.updateDistribution();
 
   for (Element* currentElement = &targetElement; currentElement;
        currentElement = currentElement->parentElement()) {
     for (const auto& selector : m_selectors) {
       if (selectorMatches(*selector, *currentElement, targetElement))
         return currentElement;
     }
@@ skipping 407 matching lines @@
   }
 
   findTraverseRootsAndExecute<SelectorQueryTrait>(rootNode, output);
 }
 
 std::unique_ptr<SelectorQuery> SelectorQuery::adopt(
     CSSSelectorList selectorList) {
   return WTF::wrapUnique(new SelectorQuery(std::move(selectorList)));
 }
 
-SelectorQuery::SelectorQuery(CSSSelectorList selectorList) {
-  m_selectorList = std::move(selectorList);
-  DCHECK(m_selectors.isEmpty());
-
-  unsigned selectorCount = 0;
-  for (const CSSSelector* selector = m_selectorList.first(); selector;
-       selector = CSSSelectorList::next(*selector))
-    selectorCount++;
-
-  m_usesDeepCombinatorOrShadowPseudo = false;
-  m_needsUpdatedDistribution = false;
-  m_selectors.reserveInitialCapacity(selectorCount);
+SelectorQuery::SelectorQuery(CSSSelectorList selectorList)
+    : m_selectorList(std::move(selectorList)),
+      m_usesDeepCombinatorOrShadowPseudo(false),
+      m_needsUpdatedDistribution(false) {
+  m_selectors.reserveInitialCapacity(m_selectorList.computeLength());
   for (const CSSSelector* selector = m_selectorList.first(); selector;
        selector = CSSSelectorList::next(*selector)) {
     if (selector->matchesPseudoElement())
       continue;
     m_selectors.uncheckedAppend(selector);
     m_usesDeepCombinatorOrShadowPseudo |=
         selector->hasDeepCombinatorOrShadowPseudo();
     m_needsUpdatedDistribution |= selector->needsUpdatedDistribution();
   }
 }
@@ skipping 30 matching lines @@
   return m_entries
       .insert(selectors, SelectorQuery::adopt(std::move(selectorList)))
       .storedValue->value.get();
 }
 
 void SelectorQueryCache::invalidate() {
   m_entries.clear();
 }
 
 }  // namespace blink