document.lastModified should consider user's local time zone

Source/core/html/forms/MonthInputType.cpp

 /*
  * Copyright (C) 2010 Google Inc. All rights reserved.
  *
  * Redistribution and use in source and binary forms, with or without
  * modification, are permitted provided that the following conditions are
  * met:
  *
  *     * Redistributions of source code must retain the above copyright
  * notice, this list of conditions and the following disclaimer.
  *     * Redistributions in binary form must reproduce the above
@@ skipping 68 matching lines @@
 String MonthInputType::serializeWithMilliseconds(double value) const
 {
     DateComponents date;
     if (!date.setMillisecondsSinceEpochForMonth(value))
         return String();
     return serializeWithComponents(date);
 }
 
 Decimal MonthInputType::defaultValueForStepUp() const
 {
-    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()));
     double months = date.monthsSinceEpoch();
     ASSERT(std::isfinite(months));
     return Decimal::fromDouble(months);
 }
 
 StepRange MonthInputType::createStepRange(AnyStepHandling anyStepHandling) const
 {
     DEFINE_STATIC_LOCAL(const StepRange::StepDescription, stepDescription, (monthDefaultStep, monthDefaultStepBase, monthStepScaleFactor, StepRange::ParsedStepValueShouldBeInteger));
 
     return InputType::createStepRange(anyStepHandling, Decimal::fromDouble(monthDefaultStepBase), Decimal::fromDouble(DateComponents::minimumMonth()), Decimal::fromDouble(DateComponents::maximumMonth()), stepDescription);
@@ skipping 51 matching lines @@
     layoutParameters.placeholderForMonth = "--";
     layoutParameters.placeholderForYear = "----";
 }
 
 bool MonthInputType::isValidFormat(bool hasYear, bool hasMonth, bool hasWeek, bool hasDay, bool hasAMPM, bool hasHour, bool hasMinute, bool hasSecond) const
 {
     return hasYear && hasMonth;
 }
 #endif
 } // namespace blink