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

src/objects.h

Index: src/objects.h
diff --git a/src/objects.h b/src/objects.h
index c2e4983abe2c3f5ef8826d752af0c692dcd013cd..7e2530188892204951b4862e0067e8a0a8bd6f9f 100644
--- a/src/objects.h
+++ b/src/objects.h
@@ -10331,6 +10331,7 @@ class CallHandlerInfo: public Struct {
  public:
   DECL_ACCESSORS(callback, Object)
   DECL_ACCESSORS(data, Object)
+  DECL_ACCESSORS(fast_handler, Object)
 
   DECLARE_CAST(CallHandlerInfo)
 
@@ -10340,7 +10341,8 @@ class CallHandlerInfo: public Struct {
 
   static const int kCallbackOffset = HeapObject::kHeaderSize;
   static const int kDataOffset = kCallbackOffset + kPointerSize;
-  static const int kSize = kDataOffset + kPointerSize;
+  static const int kFastHandlerOffset = kDataOffset + kPointerSize;
+  static const int kSize = kFastHandlerOffset + kPointerSize;
 
  private:
   DISALLOW_IMPLICIT_CONSTRUCTORS(CallHandlerInfo);