It died recently.
Note that the absence of the Invoke abstract operation in Rev 21 is a bug. It will be back in Rev 22 so you should feel free to use it. Only the [[Invoke]] internal method has died
7.3.10 Invoke(O,P, [args])
The abstract operation Invoke is used to call a method property of an object. The operation is called with arguments O, P , and optionally args where O serves as both the lookup point for the property and the this value of the call, P is the property key, and args is the list of arguments values passed to the method. If args is not present, an empty List is used as its value. This abstract operation performs the following steps:
Oh, well, in that case we're fine; we only use the Invoke abstract operation. Thanks @allenwb!