[date] Refactor TimezoneCache to be separate from the OS

src/base/platform/platform.h

Index: src/base/platform/platform.h
diff --git a/src/base/platform/platform.h b/src/base/platform/platform.h
index 374cddfc0c39c989adce633cda4c33ca07acdbb9..018d9e7a9c74ca203bd6de7c44a530dcf7ded276 100644
--- a/src/base/platform/platform.h
+++ b/src/base/platform/platform.h
@@ -124,19 +124,6 @@ class V8_BASE_EXPORT OS {
   static double TimeCurrentMillis();
 
   static TimezoneCache* CreateTimezoneCache();
-  static void DisposeTimezoneCache(TimezoneCache* cache);
-  static void ClearTimezoneCache(TimezoneCache* cache);
-
-  // Returns a string identifying the current time zone. The
-  // timestamp is used for determining if DST is in effect.
-  static const char* LocalTimezone(double time, TimezoneCache* cache);
-
-  // Returns the local time offset in milliseconds east of UTC without
-  // taking daylight savings time into account.
-  static double LocalTimeOffset(TimezoneCache* cache);
-
-  // Returns the daylight savings offset for the given time.
-  static double DaylightSavingsOffset(double time, TimezoneCache* cache);
 
   // Returns last OS error.
   static int GetLastError();