Eliminate zero count allocations from profile

src/profiler/sampling-heap-profiler.cc

Index: src/profiler/sampling-heap-profiler.cc
diff --git a/src/profiler/sampling-heap-profiler.cc b/src/profiler/sampling-heap-profiler.cc
index a32cae3ef9c926c77aa448d614ca7ed2793cbec7..61e4897b31d8e4431f7cbf5500c4bb53970c50f2 100644
--- a/src/profiler/sampling-heap-profiler.cc
+++ b/src/profiler/sampling-heap-profiler.cc
@@ -117,6 +117,9 @@ void SamplingHeapProfiler::OnWeakCallback(
   AllocationNode* node = sample->owner;
   DCHECK(node->allocations_[sample->size] > 0);
   node->allocations_[sample->size]--;
+  if (node->allocations_[sample->size] == 0) {
+    node->allocations_.erase(sample->size);
+  }
   sample->profiler->samples_.erase(sample);
   delete sample;
 }