Initialize non-product members of ClassTable.

runtime/vm/class_table.cc

Index: runtime/vm/class_table.cc
diff --git a/runtime/vm/class_table.cc b/runtime/vm/class_table.cc
index 19fd0427402598ba35f24b82d4f13e331fef6aeb..9aba86bb503823c7ee5023ac9eb240031cc60d7a 100644
--- a/runtime/vm/class_table.cc
+++ b/runtime/vm/class_table.cc
@@ -20,6 +20,8 @@ DEFINE_FLAG(bool, print_class_table, false, "Print initial class table.");
 ClassTable::ClassTable()
     : top_(kNumPredefinedCids), capacity_(0), table_(NULL),
       old_tables_(new MallocGrowableArray<RawClass**>()) {
+  NOT_IN_PRODUCT(class_heap_stats_table_ = NULL);
+  NOT_IN_PRODUCT(predefined_class_heap_stats_table_ = NULL);
   if (Dart::vm_isolate() == NULL) {
     capacity_ = initial_capacity_;
     table_ = reinterpret_cast<RawClass**>(