Add IsCallable method for Object in the API

include/v8.h

 // Copyright 2011 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 1589 matching lines @@
   V8EXPORT void SetIndexedPropertiesToExternalArrayData(
       void* data,
       ExternalArrayType array_type,
       int number_of_elements);
   V8EXPORT bool HasIndexedPropertiesInExternalArrayData();
   V8EXPORT void* GetIndexedPropertiesExternalArrayData();
   V8EXPORT ExternalArrayType GetIndexedPropertiesExternalArrayDataType();
   V8EXPORT int GetIndexedPropertiesExternalArrayDataLength();
 
   /**
+   * Checks whether a callback is set by the
+   * ObjectTemplate::SetCallAsFunctionHandler method.
+   * When an Object is callable this method returns true.
+   */
+  V8EXPORT bool IsCallable();
+
+  /**
    * Call an Object as a function if a callback is set by the 
    * ObjectTemplate::SetCallAsFunctionHandler method.
    */
   V8EXPORT Local<Value> CallAsFunction(Handle<Object> recv,
                                        int argc,
                                        Handle<Value> argv[]);
 
   /**
    * Call an Object as a consturctor if a callback is set by the
    * ObjectTemplate::SetCallAsFunctionHandler method.
@@ skipping 2462 matching lines @@
 
 
 }  // namespace v8
 
 
 #undef V8EXPORT
 #undef TYPE_CHECK
 
 
 #endif  // V8_H_