Off-by-one error in zapping objects after right trimming.

src/objects.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 2158 matching lines @@
   return heap->the_hole_value();
 }
 
 
 enum RightTrimMode { FROM_GC, FROM_MUTATOR };
 
 
 static void ZapEndOfFixedArray(Address new_end, int to_trim) {
   // If we are doing a big trim in old space then we zap the space.
   Object** zap = reinterpret_cast<Object**>(new_end);
+  zap++;  // Header of filler must be at least one word so skip that.
   for (int i = 1; i < to_trim; i++) {
     *zap++ = Smi::FromInt(0);
   }
 }
 
+
 template<RightTrimMode trim_mode>
 static void RightTrimFixedArray(Heap* heap, FixedArray* elms, int to_trim) {
   ASSERT(elms->map() != HEAP->fixed_cow_array_map());
   // For now this trick is only applied to fixed arrays in new and paged space.
   ASSERT(!HEAP->lo_space()->Contains(elms));
 
   const int len = elms->length();
 
   ASSERT(to_trim < len);
 
@@ skipping 11354 matching lines @@
   set_year(Smi::FromInt(year), SKIP_WRITE_BARRIER);
   set_month(Smi::FromInt(month), SKIP_WRITE_BARRIER);
   set_day(Smi::FromInt(day), SKIP_WRITE_BARRIER);
   set_weekday(Smi::FromInt(weekday), SKIP_WRITE_BARRIER);
   set_hour(Smi::FromInt(hour), SKIP_WRITE_BARRIER);
   set_min(Smi::FromInt(min), SKIP_WRITE_BARRIER);
   set_sec(Smi::FromInt(sec), SKIP_WRITE_BARRIER);
 }
 
 } }  // namespace v8::internal