Make sure Bigint._digits is always a Uint32List (instead of sometimes null).

runtime/vm/dart_api_message.cc

 // Copyright (c) 2012, the Dart project authors.  Please see the AUTHORS file
 // for details. All rights reserved. Use of this source code is governed by a
 // BSD-style license that can be found in the LICENSE file.
 
 #include "vm/dart_api_message.h"
 #include "vm/object.h"
 #include "vm/snapshot_ids.h"
 #include "vm/symbols.h"
 #include "vm/unicode.h"
 
@@ skipping 73 matching lines @@
 }
 
 
 Dart_CObject* ApiMessageReader::AllocateDartCObjectInt64(int64_t val) {
   Dart_CObject* value = AllocateDartCObject(Dart_CObject_kInt64);
   value->value.as_int64 = val;
   return value;
 }
 
 
+_Dart_CObject* ApiMessageReader::singleton_uint32_typed_data_ = NULL;
+
 Dart_CObject* ApiMessageReader::AllocateDartCObjectBigint() {
   Dart_CObject* value = AllocateDartCObject(Dart_CObject_kBigint);
   value->value.as_bigint.neg = false;
   value->value.as_bigint.used = 0;
-  value->value.as_bigint.digits = NULL;
+  if (singleton_uint32_typed_data_ == NULL) {
+    singleton_uint32_typed_data_ =
+        AllocateDartCObjectTypedData(Dart_TypedData_kUint32, 0);
+  }
+  value->value.as_bigint.digits = singleton_uint32_typed_data_;
   value->type = Dart_CObject_kBigint;
   return value;
 }
 
 
 Dart_CObject* ApiMessageReader::AllocateDartCObjectDouble(double val) {
   Dart_CObject* value = AllocateDartCObject(Dart_CObject_kDouble);
   value->value.as_double = val;
   return value;
 }
@@ skipping 1106 matching lines @@
     if (!success) {
       UnmarkAllCObjects(object);
       return false;
     }
   }
   UnmarkAllCObjects(object);
   return true;
 }
 
 }  // namespace dart