[date] Refactor TimezoneCache to be separate from the OS

src/base/platform/platform-freebsd.cc

Index: src/base/platform/platform-freebsd.cc
diff --git a/src/base/platform/platform-freebsd.cc b/src/base/platform/platform-freebsd.cc
index efb1872f3576bb0ba05732e7406d32bdeb151712..39036455c964dd43fcbd4b95b70995d88f03070c 100644
--- a/src/base/platform/platform-freebsd.cc
+++ b/src/base/platform/platform-freebsd.cc
@@ -29,32 +29,13 @@
 #undef MAP_TYPE
 
 #include "src/base/macros.h"
+#include "src/base/platform/platform-posix.h"
 #include "src/base/platform/platform.h"
 
-
 namespace v8 {
 namespace base {
 
-
-const char* OS::LocalTimezone(double time, TimezoneCache* cache) {
-  if (std::isnan(time)) return "";
-  time_t tv = static_cast<time_t>(std::floor(time/msPerSecond));
-  struct tm tm;
-  struct tm* t = localtime_r(&tv, &tm);
-  if (NULL == t) return "";
-  return t->tm_zone;
-}
-
-
-double OS::LocalTimeOffset(TimezoneCache* cache) {
-  time_t tv = time(NULL);
-  struct tm tm;
-  struct tm* t = localtime_r(&tv, &tm);
-  // tm_gmtoff includes any daylight savings offset, so subtract it.
-  return static_cast<double>(t->tm_gmtoff * msPerSecond -
-                             (t->tm_isdst > 0 ? 3600 * msPerSecond : 0));
-}
-
+TimezoneCache* OS::CreateTimezoneCache() { return new PosixTimezoneCache(); }
 
 void* OS::Allocate(const size_t requested,
                    size_t* allocated,