Don't shrink new space based on allocation rate in predictable mode.

src/heap/heap.cc

 // 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.
 
 #include "src/v8.h"
 
 #include "src/accessors.h"
 #include "src/api.h"
 #include "src/base/bits.h"
 #include "src/base/once.h"
@@ skipping 4552 matching lines @@
 
 
 bool Heap::HasLowAllocationRate(size_t allocation_rate) {
   static const size_t kLowAllocationRate = 1000;
   if (allocation_rate == 0) return false;
   return allocation_rate < kLowAllocationRate;
 }
 
 
 void Heap::ReduceNewSpaceSize(size_t allocation_rate) {
-  if (HasLowAllocationRate(allocation_rate)) {
+  if (!FLAG_predictable && HasLowAllocationRate(allocation_rate)) {
     new_space_.Shrink();
     UncommitFromSpace();
   }
 }
 
 
 bool Heap::TryFinalizeIdleIncrementalMarking(
     double idle_time_in_ms, size_t size_of_objects,
     size_t final_incremental_mark_compact_speed_in_bytes_per_ms) {
   if (FLAG_overapproximate_weak_closure &&
@@ skipping 2002 matching lines @@
     *object_type = "CODE_TYPE";                                                \
     *object_sub_type = "CODE_AGE/" #name;                                      \
     return true;
     CODE_AGE_LIST_COMPLETE(COMPARE_AND_RETURN_NAME)
 #undef COMPARE_AND_RETURN_NAME
   }
   return false;
 }
 }
 }  // namespace v8::internal