Add a flag to trace heap object stats on GC.

src/heap/mark-compact.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/base/atomicops.h"
 #include "src/base/bits.h"
 #include "src/code-stubs.h"
 #include "src/compilation-cache.h"
@@ skipping 2367 matching lines @@
   if (is_code_flushing_enabled()) {
     code_flusher_->ProcessCandidates();
     // If incremental marker does not support code flushing, we need to
     // disable it before incremental marking steps for next cycle.
     if (FLAG_flush_code && !FLAG_flush_code_incrementally) {
       EnableCodeFlushing(false);
     }
   }
 
   if (FLAG_track_gc_object_stats) {
+    if (FLAG_trace_gc_object_stats) {
+      heap()->TraceObjectStats();
+    }
     heap()->CheckpointObjectStats();
   }
 }
 
 
 void MarkCompactCollector::ClearNonLiveReferences() {
   // Iterate over the map space, setting map transitions that go from
   // a marked map to an unmarked map to null transitions.  This action
   // is carried out only on maps of JSObjects and related subtypes.
   HeapObjectIterator map_iterator(heap()->map_space());
@@ skipping 2342 matching lines @@
   SlotsBuffer* buffer = *buffer_address;
   while (buffer != NULL) {
     SlotsBuffer* next_buffer = buffer->next();
     DeallocateBuffer(buffer);
     buffer = next_buffer;
   }
   *buffer_address = NULL;
 }
 }
 }  // namespace v8::internal