Add safe handling of NaN to Posix platform-dependent time functions.

src/date-delay.js

 // Copyright 2006-2008 the V8 project authors. All rights reserved.
 // Redistribution and use in source and binary forms, with or without
 // modification, are permitted provided that the following conditions are
 // met:
 //
 //     * Redistributions of source code must retain the above copyright
 //       notice, this list of conditions and the following disclaimer.
 //     * Redistributions in binary form must reproduce the above
 //       copyright notice, this list of conditions and the following
 //       disclaimer in the documentation and/or other materials provided
@@ skipping 138 matching lines @@
   offset: 0,
   // Time interval where the cached offset is valid.
   start: 0, end: -1,
   // Size of next interval expansion.
   increment: 0
 };
 
 
 // NOTE: The implementation relies on the fact that no time zones have
 // more than one daylight savings offset change per month.
-// This function must never be called with the argument NaN.
-// All uses of it are guarded so this does not happen.
+// If this function is called with NaN it returns NaN.
 function DaylightSavingsOffset(t) {
   // Load the cache object from the builtins object.
   var cache = DST_offset_cache;
 
   // Cache the start and the end in local variables for fast access.
   var start = cache.start;
   var end = cache.end;
 
   if (start <= t) {
     // If the time fits in the cached interval, return the cached offset.
@@ skipping 474 matching lines @@
 
 
 function TimeString(time) {
   return TwoDigitString(HourFromTime(time)) + ':'
       + TwoDigitString(MinFromTime(time)) + ':'
       + TwoDigitString(SecFromTime(time));
 }
 
 
 function LocalTimezoneString(time) {
-  // time is not NaN because of checks in calling functions.
-  var timezoneOffset = (local_time_offset + DaylightSavingsOffset(time)) / msPerMinute;
+  var timezoneOffset =
+      (local_time_offset + DaylightSavingsOffset(time)) / msPerMinute;
   var sign = (timezoneOffset >= 0) ? 1 : -1;
   var hours = FLOOR((sign * timezoneOffset)/60);
   var min   = FLOOR((sign * timezoneOffset)%60);
-  var gmt = ' GMT' + ((sign == 1) ? '+' : '-') + TwoDigitString(hours) + TwoDigitString(min);
+  var gmt = ' GMT' + ((sign == 1) ? '+' : '-') +
+      TwoDigitString(hours) + TwoDigitString(min);
   return gmt + ' (' +  LocalTimezone(time) + ')';
 }
 
 
 function DatePrintString(time) {
   return DateString(time) + ' ' + TimeString(time);
 }
 
 // -------------------------------------------------------------------
 
@@ skipping 493 matching lines @@
     "toGMTString", DateToGMTString,
     "toUTCString", DateToUTCString,
     "getYear", DateGetYear,
     "setYear", DateSetYear,
     "toISOString", DateToISOString,
     "toJSON", DateToJSON
   ));
 }
 
 SetupDate();