foo.js

function InstantiateFunction(data, name) {
  // We need a reference to kApiFunctionCache in the stack frame
  // if we need to bail out from a stack overflow.
  var cache = kApiFunctionCache;
  var serialNumber = %GetTemplateField(data, kApiSerialNumberOffset);
  var isFunctionCached =
   (serialNumber in cache) && (cache[serialNumber] != kUninitialized);
  if (!isFunctionCached) {
    try {
      cache[serialNumber] = null;
      var fun = %CreateApiFunction(data);
      if (name) %FunctionSetName(fun, name);
      cache[serialNumber] = fun;
      var prototype = %GetTemplateField(data, kApiPrototypeTemplateOffset);
      fun.prototype = prototype ? Instantiate(prototype) : {};
      %SetProperty(fun.prototype, "constructor", fun, DONT_ENUM);
      var parent = %GetTemplateField(data, kApiParentTemplateOffset);
      if (parent) {
        var parent_fun = Instantiate(parent);
        fun.prototype.__proto__ = parent_fun.prototype;
      }
      ConfigureTemplateInstance(fun, data);
    } catch (e) {
      cache[serialNumber] = kUninitialized;
      throw e;
    }
  }
  return cache[serialNumber];
}

What is this?

v8's function init code, Tim was wondering where .constructor came from