Only shrink new space when we are not in the process of obtaining pretenuring feedback.

src/heap/heap.h

 // Copyright 2012 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.
 
 #ifndef V8_HEAP_HEAP_H_
 #define V8_HEAP_HEAP_H_
 
 #include <cmath>
 #include <map>
 
@@ skipping 1844 matching lines @@
   // reporting/verification activities when compiled with DEBUG set.
   void GarbageCollectionPrologue();
   void GarbageCollectionEpilogue();
 
   void PreprocessStackTraces();
 
   // Pretenuring decisions are made based on feedback collected during new
   // space evacuation. Note that between feedback collection and calling this
   // method object in old space must not move.
   // Right now we only process pretenuring feedback in high promotion mode.
-  void ProcessPretenuringFeedback();
+  bool ProcessPretenuringFeedback();
 
   // Checks whether a global GC is necessary
   GarbageCollector SelectGarbageCollector(AllocationSpace space,
                                           const char** reason);
 
   // Make sure there is a filler value behind the top of the new space
   // so that the GC does not confuse some unintialized/stale memory
   // with the allocation memento of the object at the top
   void EnsureFillerObjectAtTop();
 
@@ skipping 947 matching lines @@
   DisallowHeapAllocation no_allocation;  // i.e. no gc allowed.
 
  private:
   DISALLOW_IMPLICIT_CONSTRUCTORS(PathTracer);
 };
 #endif  // DEBUG
 }
 }  // namespace v8::internal
 
 #endif  // V8_HEAP_HEAP_H_