Initialize member array field.

third_party/WebKit/Source/core/css/RuleSet.cpp

 /*
  * Copyright (C) 1999 Lars Knoll (knoll@kde.org)
  *           (C) 2004-2005 Allan Sandfeld Jensen (kde@carewolf.com)
  * Copyright (C) 2006, 2007 Nicholas Shanks (webkit@nickshanks.com)
  * Copyright (C) 2005, 2006, 2007, 2008, 2009, 2010, 2011, 2012 Apple Inc. All
  * rights reserved.
  * Copyright (C) 2007 Alexey Proskuryakov <ap@webkit.org>
  * Copyright (C) 2007, 2008 Eric Seidel <eric@webkit.org>
  * Copyright (C) 2008, 2009 Torch Mobile Inc. All rights reserved.
  * (http://www.torchmobile.com/)
@@ skipping 111 matching lines @@
     : m_rule(rule),
       m_selectorIndex(selectorIndex),
       m_isLastInArray(false),
       m_position(position),
       m_specificity(selector().specificity()),
       m_containsUncommonAttributeSelector(
           blink::containsUncommonAttributeSelector(selector())),
       m_linkMatchType(selector().computeLinkMatchType()),
       m_hasDocumentSecurityOrigin(addRuleFlags & RuleHasDocumentSecurityOrigin),
       m_propertyWhitelist(
-          determinePropertyWhitelistType(addRuleFlags, selector())) {
+          determinePropertyWhitelistType(addRuleFlags, selector())),
+      m_descendantSelectorIdentifierHashes() {
   SelectorFilter::collectIdentifierHashes(
       selector(), m_descendantSelectorIdentifierHashes, maximumIdentifierCount);
 }
 
 void RuleSet::addToRuleSet(const AtomicString& key,
                            PendingRuleMap& map,
                            const RuleData& ruleData) {
   Member<HeapLinkedStack<RuleData>>& rules =
       map.add(key, nullptr).storedValue->value;
   if (!rules)
@@ skipping 282 matching lines @@
 }
 
 #ifndef NDEBUG
 void RuleSet::show() const {
   for (const auto& rule : m_allRules)
     rule.selector().show();
 }
 #endif
 
 }  // namespace blink