Check and clear date cache in DateCurrentTime, DateLocalTimezone and getTimezoneOffset.

src/objects.cc

 // Copyright 2013 the V8 project authors. 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
 //       copyright notice, this list of conditions and the following
 //       disclaimer in the documentation and/or other materials provided
@@ skipping 16306 matching lines @@
 Object* JSDate::GetUTCField(FieldIndex index,
                             double value,
                             DateCache* date_cache) {
   ASSERT(index >= kFirstUTCField);
 
   if (std::isnan(value)) return GetIsolate()->heap()->nan_value();
 
   int64_t time_ms = static_cast<int64_t>(value);
 
   if (index == kTimezoneOffset) {
+    date_cache->CheckTimezone();
     return Smi::FromInt(date_cache->TimezoneOffset(time_ms));
   }
 
   int days = DateCache::DaysFromTime(time_ms);
 
   if (index == kWeekdayUTC) return Smi::FromInt(date_cache->Weekday(days));
 
   if (index <= kDayUTC) {
     int year, month, day;
     date_cache->YearMonthDayFromDays(days, &year, &month, &day);
@@ skipping 143 matching lines @@
 #define ERROR_MESSAGES_TEXTS(C, T) T,
   static const char* error_messages_[] = {
       ERROR_MESSAGES_LIST(ERROR_MESSAGES_TEXTS)
   };
 #undef ERROR_MESSAGES_TEXTS
   return error_messages_[reason];
 }
 
 
 } }  // namespace v8::internal