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 - DST applies, ==0 - DST does not apply, <0 - 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

Author: akosthekiss

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

@@ -479,7 +479,7 @@ ecma_date_daylight_saving_ta (ecma_number_t time) /**< time value */
     return ecma_number_make_nan ();
   }
 
-  return tz.daylight_saving_time;
+  return tz.daylight_saving_time * ECMA_DATE_MS_PER_HOUR;
 } /* ecma_date_daylight_saving_ta */
 
 /**

jerry-core/jerry-port.h

@@ -82,7 +82,7 @@ void jerry_port_fatal (jerry_fatal_code_t code);
 typedef struct
 {
   int offset;                /**< minutes from west */
-  int daylight_saving_time;  /**< daylight saving time */
+  int daylight_saving_time;  /**< daylight saving time (1 - DST applies, 0 - not on DST) */
 } jerry_time_zone_t;
 
 /**

targets/default/jerry-port-default-date.c

@@ -35,7 +35,7 @@ bool jerry_port_get_time_zone (jerry_time_zone_t *tz_p)
   gettimeofday (&tv, &tz);
 
   tz_p->offset = tz.tz_minuteswest;
-  tz_p->daylight_saving_time = tz.tz_dsttime;
+  tz_p->daylight_saving_time = tz.tz_dsttime > 0 ? 1 : 0;
 
   return true;
 } /* jerry_port_get_time_zone */