WTF/std normalization: replace WTF::Vector::last with ::back

third_party/WebKit/Source/core/timing/PerformanceUserTiming.cpp

Index: third_party/WebKit/Source/core/timing/PerformanceUserTiming.cpp
diff --git a/third_party/WebKit/Source/core/timing/PerformanceUserTiming.cpp b/third_party/WebKit/Source/core/timing/PerformanceUserTiming.cpp
index 7146f3012d2e04e30296ccef75f8a2aaf9589aca..b4c66c7656d7a6d30dd092a6c111e70f1bd587d7 100644
--- a/third_party/WebKit/Source/core/timing/PerformanceUserTiming.cpp
+++ b/third_party/WebKit/Source/core/timing/PerformanceUserTiming.cpp
@@ -131,7 +131,7 @@ void UserTiming::clearMarks(const String& markName) {
 double UserTiming::findExistingMarkStartTime(const String& markName,
                                              ExceptionState& exceptionState) {
   if (m_marksMap.contains(markName))
-    return m_marksMap.get(markName).last()->startTime();
+    return m_marksMap.get(markName).back()->startTime();
 
   if (restrictedKeyMap().contains(markName) && m_performance->timing()) {
     double value = static_cast<double>(