document.lastModified should consider user's local time zone

Source/core/html/shadow/DateTimeFieldElements.cpp

Index: Source/core/html/shadow/DateTimeFieldElements.cpp
diff --git a/Source/core/html/shadow/DateTimeFieldElements.cpp b/Source/core/html/shadow/DateTimeFieldElements.cpp
index 2a324e2610fa03cac4912b437e533d6cbc736d21..e8047e1cd5e62de5ed221609bceedac9cc4cd0c7 100644
--- a/Source/core/html/shadow/DateTimeFieldElements.cpp
+++ b/Source/core/html/shadow/DateTimeFieldElements.cpp
@@ -589,14 +589,8 @@ PassRefPtrWillBeRawPtr<DateTimeYearFieldElement> DateTimeYearFieldElement::creat
 
 static int currentFullYear()
 {
-    double current = currentTimeMS();
-    double utcOffset = calculateUTCOffset();
-    double dstOffset = calculateDSTOffset(current, utcOffset);
-    int offset = static_cast<int>((utcOffset + dstOffset) / msPerMinute);
-    current += offset * msPerMinute;
-
     DateComponents date;
-    date.setMillisecondsSinceEpochForMonth(current);
+    date.setMillisecondsSinceEpochForMonth(convertToLocalTime(currentTimeMS()));
     return date.fullYear();
 }