Pass in the prototype to CreateApiFunction rather than setting it on the result.

src/runtime.h

 // Copyright 2012 the V8 project authors. All rights reserved.
 // Redistribution and use in source and binary forms, with or without
 // modification, are permitted provided that the following conditions are
 // met:
 //
 //     * Redistributions of source code must retain the above copyright
 //       notice, this list of conditions and the following disclaimer.
 //     * Redistributions in binary form must reproduce the above
 //       copyright notice, this list of conditions and the following
 //       disclaimer in the documentation and/or other materials provided
@@ skipping 208 matching lines @@
   F(FunctionIsAPIFunction, 1, 1) \
   F(FunctionIsBuiltin, 1, 1) \
   F(GetScript, 1, 1) \
   F(CollectStackTrace, 3, 1) \
   F(GetAndClearOverflowedStackTrace, 1, 1) \
   F(GetV8Version, 0, 1) \
   \
   F(SetCode, 2, 1) \
   F(SetExpectedNumberOfProperties, 2, 1) \
   \
-  F(CreateApiFunction, 1, 1) \
+  F(CreateApiFunction, 2, 1) \
   F(IsTemplate, 1, 1) \
   F(GetTemplateField, 2, 1) \
   F(DisableAccessChecks, 1, 1) \
   F(EnableAccessChecks, 1, 1) \
   F(SetAccessorProperty, 6, 1) \
   \
   /* Dates */ \
   F(DateCurrentTime, 0, 1) \
   F(DateParseString, 2, 1) \
   F(DateLocalTimezone, 1, 1) \
@@ skipping 670 matching lines @@
 class AllocateDoubleAlignFlag:  public BitField<bool,            0, 1> {};
 class AllocateTargetSpace:      public BitField<AllocationSpace, 1, 3> {};
 
 class DeclareGlobalsEvalFlag:   public BitField<bool,       0, 1> {};
 class DeclareGlobalsNativeFlag: public BitField<bool,       1, 1> {};
 class DeclareGlobalsStrictMode: public BitField<StrictMode, 2, 1> {};
 
 } }  // namespace v8::internal
 
 #endif  // V8_RUNTIME_H_