Make function lookup in classes thread-safe:

runtime/vm/resolver.h

 // Copyright (c) 2011, 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_RESOLVER_H_
 #define VM_RESOLVER_H_
 
 #include "vm/allocation.h"
 
 namespace dart {
@@ skipping 10 matching lines @@
 
 // Resolver abstracts functionality needed to resolve dart functions at
 // invocations.
 class Resolver : public AllStatic {
  public:
   // Resolve specified dart instance function.
   static RawFunction* ResolveDynamic(const Instance& receiver,
                                      const String& function_name,
                                      const ArgumentsDescriptor& args_desc);
 
+  // If 'allow_add' is true we may add a function to the class during lookup.
   static RawFunction* ResolveDynamicForReceiverClass(
       const Class& receiver_class,
       const String& function_name,
-      const ArgumentsDescriptor& args_desc);
+      const ArgumentsDescriptor& args_desc,
+      bool allow_add = true);
 
+  // If 'allow_add' is true we may add a function to the class during lookup.
   static RawFunction* ResolveDynamicAnyArgs(
       const Class& receiver_class,
-      const String& function_name);
+      const String& function_name,
+      bool allow_add = true);
 
   // Resolve specified dart static function. If library.IsNull, use
   // either application library or core library if no application library
   // exists. Passing negative num_arguments means that the function
   // will be resolved by name only.
   // Otherwise null is returned if the number or names of arguments are not
   // valid for the resolved function.
   static RawFunction* ResolveStatic(const Library& library,
                                     const String& cls_name,
                                     const String& function_name,
@@ skipping 11 matching lines @@
   // public and private functions.
   static RawFunction* ResolveStaticAllowPrivate(const Class&  cls,
                                                 const String& function_name,
                                                 intptr_t num_arguments,
                                                 const Array& argument_names);
 };
 
 }  // namespace dart
 
 #endif  // VM_RESOLVER_H_