Reset old generation limit on main frame context disposal.

src/heap/gc-tracer.cc

 // Copyright 2014 the V8 project authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #include "src/v8.h"
 
 #include "src/heap/gc-tracer.h"
 
 namespace v8 {
 namespace internal {
@@ skipping 569 matching lines @@
     ++iter;
   }
 
   return sum_of_rates / static_cast<double>(survival_events_.size());
 }
 
 
 bool GCTracer::SurvivalEventsRecorded() const {
   return survival_events_.size() > 0;
 }
+
+
+void GCTracer::ResetSurvivalEvents() { survival_events_.reset(); }
 }
 }  // namespace v8::internal