Don't crash if we get a timezone change notification on an uninitialized isolate

src/date.cc

 // Copyright 2012 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 31 matching lines @@
 static const int kDays1970to2000 = 30 * 365 + 7;
 static const int kDaysOffset = 1000 * kDaysIn400Years + 5 * kDaysIn400Years -
                                kDays1970to2000;
 static const int kYearsOffset = 400000;
 static const char kDaysInMonths[] =
     {31, 28, 31, 30, 31, 30, 31, 31, 30, 31, 30, 31};
 
 
 void DateCache::ResetDateCache() {
   static const int kMaxStamp = Smi::kMaxValue;
-  stamp_ = Smi::FromInt(stamp_->value() + 1);
-  if (stamp_->value() > kMaxStamp) {
+  if (stamp_->value() >= kMaxStamp) {
     stamp_ = Smi::FromInt(0);
+  } else {
+    stamp_ = Smi::FromInt(stamp_->value() + 1);
   }
   ASSERT(stamp_ != Smi::FromInt(kInvalidStamp));
   for (int i = 0; i < kDSTSize; ++i) {
     ClearSegment(&dst_[i]);
   }
   dst_usage_counter_ = 0;
   before_ = &dst_[0];
   after_ = &dst_[1];
   local_offset_ms_ = kInvalidLocalOffsetInMs;
   ymd_valid_ = false;
@@ skipping 310 matching lines @@
     if (&dst_[i] == skip) continue;
     if (result == NULL || result->last_used > dst_[i].last_used) {
       result = &dst_[i];
     }
   }
   ClearSegment(result);
   return result;
 }
 
 } }  // namespace v8::internal