Decrease the DST cache increment to take into account the suspension...

src/date.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 119 matching lines @@
 // Because computing the DST offset is an expensive operation,
 // we keep a cache of the last computed DST offset along with a time interval
 // where we know the cache is valid.
 // When the cache is valid, local_time_offset is also valid.
 var DST_offset_cache = {
   // Cached DST offset.
   offset: 0,
   // Time interval where the cached offset is valid.
   start: 0, end: -1,
   // Size of next interval expansion.
-  increment: 0
+  increment: 0,
+  initial_increment: 19 * msPerDay
 };
 
 
 // NOTE: The implementation relies on the fact that no time zones have
-// more than one daylight savings offset change per month.
+// more than one daylight savings offset change per 19 days.
+//
+// In Egypt in 2010 they decided to suspend DST during Ramadan. This
+// led to a short interval where DST is in effect from September 10 to
+// September 30.
+//
 // 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.
     if (t <= end) return cache.offset;
 
     // If the cache misses, the local_time_offset may not be initialized.
     if (IS_UNDEFINED(local_time_offset)) {
       local_time_offset = %DateLocalTimeOffset();
     }
 
     // Compute a possible new interval end.
     var new_end = end + cache.increment;
 
     if (t <= new_end) {
       var end_offset = %DateDaylightSavingsOffset(EquivalentTime(new_end));
       if (cache.offset == end_offset) {
         // If the offset at the end of the new interval still matches
         // the offset in the cache, we grow the cached time interval
         // and return the offset.
         cache.end = new_end;
-        cache.increment = msPerMonth;
+        cache.increment = cache.initial_increment;
         return end_offset;
       } else {
         var offset = %DateDaylightSavingsOffset(EquivalentTime(t));
         if (offset == end_offset) {
           // The offset at the given time is equal to the offset at the
           // new end of the interval, so that means that we've just skipped
           // the point in time where the DST offset change occurred. Updated
           // the interval to reflect this and reset the increment.
           cache.start = t;
           cache.end = new_end;
-          cache.increment = msPerMonth;
+          cache.increment = cache.initial_increment;
         } else {
           // The interval contains a DST offset change and the given time is
           // before it. Adjust the increment to avoid a linear search for
           // the offset change point and change the end of the interval.
           cache.increment /= 3;
           cache.end = t;
         }
         // Update the offset in the cache and return it.
         cache.offset = offset;
         return offset;
       }
     }
   }
 
   // If the cache misses, the local_time_offset may not be initialized.
   if (IS_UNDEFINED(local_time_offset)) {
     local_time_offset = %DateLocalTimeOffset();
   }
   // Compute the DST offset for the time and shrink the cache interval
   // to only contain the time. This allows fast repeated DST offset
   // computations for the same time.
   var offset = %DateDaylightSavingsOffset(EquivalentTime(t));
   cache.offset = offset;
   cache.start = cache.end = t;
-  cache.increment = msPerMonth;
+  cache.increment = cache.initial_increment;
   return offset;
 }
 
 
 var timezone_cache_time = $NaN;
 var timezone_cache_timezone;
 
 function LocalTimezone(t) {
   if (NUMBER_IS_NAN(t)) return "";
   if (t == timezone_cache_time) {
@@ skipping 829 matching lines @@
     "toGMTString", DateToGMTString,
     "toUTCString", DateToUTCString,
     "getYear", DateGetYear,
     "setYear", DateSetYear,
     "toISOString", DateToISOString,
     "toJSON", DateToJSON
   ));
 }
 
 SetupDate();