Use begin/end istead of first/last for rule ranges.

Source/core/css/ElementRuleCollector.cpp

Index: Source/core/css/ElementRuleCollector.cpp
diff --git a/Source/core/css/ElementRuleCollector.cpp b/Source/core/css/ElementRuleCollector.cpp
index dd29dc4d12e408450b31f0c49036c98fdc583dcf..80c64861f3a8d61f82d5c1bdc621eec5bef0d42c 100644
--- a/Source/core/css/ElementRuleCollector.cpp
+++ b/Source/core/css/ElementRuleCollector.cpp
@@ -271,7 +271,7 @@ void ElementRuleCollector::sortAndTransferMatchedRules()
     }
 
     if (m_matchingUARules)
-        m_result.lastUARuleIndex = m_result.matchedProperties.size() - 1;
+        m_result.uaEnd = m_result.matchedProperties.size();
 }
 
 void ElementRuleCollector::didMatchRule(const RuleData& ruleData, const SelectorChecker::MatchResult& result, CascadeOrder cascadeOrder, const MatchRequest& matchRequest)