function FunctionCall(func, thisContext, args, ret, error) {
  this.function_ = func;
  this.thisContext_ = thisContext;
  this.arguments_ = Array.prototype.slice.call(args);
  this.returnValue_ = ret;
  this.error_ = error;
}
Struct for a single function call.
@param {!Function} func The called function.
@param {!Object} thisContext `this` context of called function.
@param {!Arguments} args Arguments of the called function.
@param {*} ret Return value of the function or undefined in case of error.
@param {*} error The error thrown by the function or null if none.
@constructor