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

runtime/vm/object_store.h

 // 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.
 
 #ifndef VM_OBJECT_STORE_H_
 #define VM_OBJECT_STORE_H_
 
 #include "vm/object.h"
 
 namespace dart {
@@ skipping 397 matching lines @@
     preallocated_stack_trace_ = value.raw();
   }
 
   RawFunction* lookup_port_handler() const {
     return lookup_port_handler_;
   }
   void set_lookup_port_handler(const Function& function) {
     lookup_port_handler_ = function.raw();
   }
 
+  RawTypedData* empty_uint32_array() const {
+    return empty_uint32_array_;
+  }
+  void set_empty_uint32_array(const TypedData& array) {
+    // Only set once.
+    ASSERT(empty_uint32_array_ == TypedData::null());
+    ASSERT(!array.IsNull());
+    empty_uint32_array_ = array.raw();
+  }
+
   RawFunction* handle_message_function() const {
     return handle_message_function_;
   }
   void set_handle_message_function(const Function& function) {
     handle_message_function_ = function.raw();
   }
 
   RawUserTag* default_tag() const {
     return default_tag_;
   }
@@ skipping 96 matching lines @@
   RawGrowableObjectArray* pending_deferred_loads_;
   RawGrowableObjectArray* resume_capabilities_;
   RawError* sticky_error_;
   RawString* unhandled_exception_handler_;
   RawContext* empty_context_;
   RawInstance* stack_overflow_;
   RawInstance* out_of_memory_;
   RawUnhandledException* preallocated_unhandled_exception_;
   RawStacktrace* preallocated_stack_trace_;
   RawFunction* lookup_port_handler_;
+  RawTypedData* empty_uint32_array_;
   RawFunction* handle_message_function_;
   RawArray* library_load_error_table_;
   RawUserTag* default_tag_;
   RawObject** to() {
     return reinterpret_cast<RawObject**>(&library_load_error_table_);
   }
 
   friend class SnapshotReader;
 
   DISALLOW_COPY_AND_ASSIGN(ObjectStore);
 };
 
 }  // namespace dart
 
 #endif  // VM_OBJECT_STORE_H_