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

This reverts commit r19711 for breaking WebKit tests.
http://build.chromium.org/p/tryserver.chromium/builders/win_rel/builds/278551/steps/content_browsertests/logs/AccessibilityMessagesQueueWhileSwappedOut

TBR=ulan@chromium.org

Review URL: https://codereview.chromium.org/192903002

git-svn-id: http://v8.googlecode.com/svn/branches/bleeding_edge@19765 ce2b1a6d-e550-0410-aec6-3dcde31c8c00

src/date.h

@@ -122,13 +122,6 @@ class DateCache {
     return static_cast<int>((time_ms - local_ms) / kMsPerMin);
   }
 
-  void CheckTimezone() {
-    if (local_offset_ms_ != kInvalidLocalOffsetInMs &&
-        local_offset_ms_ != GetLocalOffsetFromOS()) {
-      ResetDateCache();
-    }
-  }
-
   // ECMA 262 - 15.9.1.9
   int64_t ToLocal(int64_t time_ms) {
     return time_ms + LocalOffsetInMs() + DaylightSavingsOffsetInMs(time_ms);

src/date.js

@@ -42,19 +42,16 @@ function ThrowDateTypeError() {
 
 
 var timezone_cache_time = NAN;
-var timezone_cache_timezone_offset = NAN;
 var timezone_cache_timezone;
 
-function LocalTimezone(t, timezone_offset) {
+function LocalTimezone(t) {
   if (NUMBER_IS_NAN(t)) return "";
-  if (t == timezone_cache_time &&
-      timezone_offset == timezone_cache_timezone_offset) {
+  if (t == timezone_cache_time) {
     return timezone_cache_timezone;
   }
   var timezone = %DateLocalTimezone(t);
   timezone_cache_time = t;
   timezone_cache_timezone = timezone;
-  timezone_cache_timezone_offset = timezone_offset;
   return timezone;
 }
 
@@ -248,8 +245,9 @@ function TimeStringUTC(date) {
 
 
 function LocalTimezoneString(date) {
+  var timezone = LocalTimezone(UTC_DATE_VALUE(date));
+
   var timezoneOffset = -TIMEZONE_OFFSET(date);
-  var timezone = LocalTimezone(UTC_DATE_VALUE(date), timezoneOffset);
   var sign = (timezoneOffset >= 0) ? 1 : -1;
   var hours = FLOOR((sign * timezoneOffset)/60);
   var min   = FLOOR((sign * timezoneOffset)%60);

src/objects.cc

@@ -16342,7 +16342,6 @@ Object* JSDate::GetUTCField(FieldIndex index,
   int64_t time_ms = static_cast<int64_t>(value);
 
   if (index == kTimezoneOffset) {
-    date_cache->CheckTimezone();
     return Smi::FromInt(date_cache->TimezoneOffset(time_ms));
   }
 

src/runtime.cc

@@ -9549,7 +9549,6 @@ RUNTIME_FUNCTION(MaybeObject*, Runtime_DateCurrentTime) {
   // time is milliseconds. Therefore, we floor the result of getting
   // the OS time.
   double millis = std::floor(OS::TimeCurrentMillis());
-  isolate->date_cache()->CheckTimezone();
   return isolate->heap()->NumberFromDouble(millis);
 }
 
@@ -9596,7 +9595,6 @@ RUNTIME_FUNCTION(MaybeObject*, Runtime_DateLocalTimezone) {
   ASSERT(args.length() == 1);
 
   CONVERT_DOUBLE_ARG_CHECKED(x, 0);
-  isolate->date_cache()->CheckTimezone();
   int64_t time = isolate->date_cache()->EquivalentTime(static_cast<int64_t>(x));
   const char* zone = OS::LocalTimezone(static_cast<double>(time));
   return isolate->heap()->AllocateStringFromUtf8(CStrVector(zone));