Adds the possibility of setting a Code object as the callback of a FunctionTemplate.

src/builtins.h

Index: src/builtins.h
diff --git a/src/builtins.h b/src/builtins.h
index c1159a8d5252848108340f6844b144a6161cb990..788aeb000fc47d10f0a549c85ed3e8dc6e0d20c9 100644
--- a/src/builtins.h
+++ b/src/builtins.h
@@ -99,6 +99,8 @@ enum BuiltinExtraArguments {
   V(ConstructProxy, BUILTIN, UNINITIALIZED, kNoExtraICState)                  \
   V(Construct, BUILTIN, UNINITIALIZED, kNoExtraICState)                       \
                                                                               \
+  V(HandleFastApiCall, BUILTIN, UNINITIALIZED, kNoExtraICState)               \
+                                                                              \
   V(InOptimizationQueue, BUILTIN, UNINITIALIZED, kNoExtraICState)             \
   V(JSConstructStubGeneric, BUILTIN, UNINITIALIZED, kNoExtraICState)          \
   V(JSConstructStubForDerived, BUILTIN, UNINITIALIZED, kNoExtraICState)       \
@@ -329,6 +331,8 @@ class Builtins {
   // ES6 section 7.3.13 Construct (F, [argumentsList], [newTarget])
   static void Generate_Construct(MacroAssembler* masm);
 
+  static void Generate_HandleFastApiCall(MacroAssembler* masm);
+
   static void Generate_FunctionCall(MacroAssembler* masm);
   static void Generate_FunctionApply(MacroAssembler* masm);
   static void Generate_ReflectApply(MacroAssembler* masm);