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 95e242c3a30b08244e1bdb58df06fa66ef2fcd0b..e22bc27ddd2971ac0c4a8b86e24dba7f1f141e6d 100644
--- a/src/builtins.h
+++ b/src/builtins.h
@@ -100,6 +100,8 @@ 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(JSBuiltinsConstructStub, BUILTIN, UNINITIALIZED, kNoExtraICState)         \
@@ -330,6 +332,8 @@ 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);