[heap] Fix tracking of fixed array sub-types in ObjectStatsCollector.

Bug: 
Change-Id: Ice28172e75a9fce1bad199b13e3fc0c123aaf42f
Reviewed-on: https://chromium-review.googlesource.com/758588Reviewed-by: Michael Lippautz <mlippautz@chromium.org>
Commit-Queue: Michael Lippautz <mlippautz@chromium.org>
Cr-Commit-Position: refs/heads/master@{#49272}

src/heap/object-stats.cc

@@ -305,8 +305,7 @@ void ObjectStatsCollector::CollectGlobalStatistics() {
 }
 
 static bool CanRecordFixedArray(Heap* heap, FixedArrayBase* array) {
-  return (array->map()->instance_type() == FIXED_ARRAY_TYPE ||
-          array->map()->instance_type() == HASH_TABLE_TYPE) &&
+  return array->map()->instance_type() == FIXED_ARRAY_TYPE &&
          array->map() != heap->fixed_double_array_map() &&
          array != heap->empty_fixed_array() &&
          array != heap->empty_byte_array() &&