Introduce the Date Port API

Replaced `gettimeofday`-related code with `jerry_port_get_current_time`
and `jerry_port_get_time_zone` function calls. Moved old code to
default port implementation.

Removed `ENABLE_DATE_SYS_CALLS` as date syscalls should "just work".

Fix DST adjustments: even if `gettimeofday` returns meaningful data in
`tz_dsttime`, the value is just a flag (or, according to some sources,
a tri-state value: >0 if DST applies, ==0 if DST does not apply, <0 if
unknown). Hitherto, the field was simply added to/subtracted from a
time value in milliseconds. To use it approximately correctly, the
field's value should be multiplied by "millisecs/hour".

JerryScript-DCO-1.0-Signed-off-by: Akos Kiss akiss@inf.u-szeged.hu

jerry-core/ecma/builtin-objects/ecma-builtin-date.c

@@ -33,10 +33,6 @@
 #define BUILTIN_UNDERSCORED_ID date
 #include "ecma-builtin-internal-routines-template.inc.h"
 
-#ifdef JERRY_ENABLE_DATE_SYS_CALLS
-#include <sys/time.h>
-#endif /* JERRY_ENABLE_DATE_SYS_CALLS */
-
 /** \addtogroup ecma ECMA
  * @{
  *
@@ -450,18 +446,8 @@ static ecma_value_t
 ecma_builtin_date_now (ecma_value_t this_arg __attr_unused___) /**< this argument */
 {
   ecma_number_t *now_num_p = ecma_alloc_number ();
-  *now_num_p = ECMA_NUMBER_ZERO;
 
-#ifdef JERRY_ENABLE_DATE_SYS_CALLS
-  struct timeval tv;
-
-  if (gettimeofday (&tv, NULL) != 0)
-  {
-    return ecma_raise_type_error (ECMA_ERR_MSG ("gettimeofday failed"));
-  }
-
-  *now_num_p = ((ecma_number_t) tv.tv_sec) * 1000.0 + ((ecma_number_t) (tv.tv_usec / 1000));
-#endif /* JERRY_ENABLE_DATE_SYS_CALLS */
+  *now_num_p = (ecma_number_t) jerry_port_get_current_time ();
 
   return ecma_make_number_value (now_num_p);
 } /* ecma_builtin_date_now */