Grow heap slower if --optimize-for-size flag is on.

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 5580 matching lines @@
   if (FLAG_trace_gc_verbose) {
     PrintIsolate(isolate_,
                  "Heap growing factor %.1f based on mu=%.3f, speed_ratio=%.f "
                  "(gc=%.f, mutator=%.f)\n",
                  factor, kTargetMutatorUtilization, gc_speed / mutator_speed,
                  gc_speed, mutator_speed);
   }
 
   // We set the old generation growing factor to 2 to grow the heap slower on
   // memory-constrained devices.
-  if (max_old_generation_size_ <= kMaxOldSpaceSizeMediumMemoryDevice) {
+  if (max_old_generation_size_ <= kMaxOldSpaceSizeMediumMemoryDevice ||
+      FLAG_optimize_for_size) {
     factor = Min(factor, kMaxHeapGrowingFactorMemoryConstrained);
   }
 
   if (FLAG_stress_compaction ||
       mark_compact_collector()->reduce_memory_footprint_) {
     factor = kMinHeapGrowingFactor;
   }
 
   // TODO(hpayer): Investigate if idle_old_generation_allocation_limit_ is still
   // needed after taking the allocation rate for the old generation limit into
@@ skipping 1249 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 internal
 }  // namespace v8