Add missing initialization for low survival rate period.

src/heap.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 119 matching lines @@
       old_gen_exhausted_(false),
       store_buffer_rebuilder_(store_buffer()),
       hidden_symbol_(NULL),
       global_gc_prologue_callback_(NULL),
       global_gc_epilogue_callback_(NULL),
       gc_safe_size_of_old_object_(NULL),
       total_regexp_code_generated_(0),
       tracer_(NULL),
       young_survivors_after_last_gc_(0),
       high_survival_rate_period_length_(0),
+      low_survival_rate_period_length_(0),
       survival_rate_(0),
       previous_survival_rate_trend_(Heap::STABLE),
       survival_rate_trend_(Heap::STABLE),
       max_gc_pause_(0),
       total_gc_time_ms_(0),
       max_alive_after_gc_(0),
       min_in_mutator_(kMaxInt),
       alive_after_last_gc_(0),
       last_gc_end_timestamp_(0.0),
       store_buffer_(this),
@@ skipping 7329 matching lines @@
       static_cast<int>(object_sizes_last_time_[index]));
   FIXED_ARRAY_SUB_INSTANCE_TYPE_LIST(ADJUST_LAST_TIME_OBJECT_COUNT)
 #undef ADJUST_LAST_TIME_OBJECT_COUNT
 
   memcpy(object_counts_last_time_, object_counts_, sizeof(object_counts_));
   memcpy(object_sizes_last_time_, object_sizes_, sizeof(object_sizes_));
   ClearObjectStats();
 }
 
 } }  // namespace v8::internal