refactor CommitInstantiated to a "method" of registry entry

[dherman]

CommitInstantiated is a weird and confusing abstract operation. Its real purpose is to flesh out the internal state of a registry entry record. This would be a little easier to understand if it were a spec "method" of a registry entry record. Also, it should have a better name.

To be clear, registry entry records are not JS objects, so I'm not talking about a JS method. But ECMA 262 does have a precedent for internal records of the semantics having methods on them.

Something like:

1. Let _status_ be _entry_.ExtractInstanceDependencies(_loader_, _optionalInstance_, _source_).

or maybe split it into two separate operations like:

1. Let _status_ be _entry_.ExtractInstance(_loader_, _optionalInstance_, _source_).
1. ReturnIfAbrupt(_status_).
1. _entry_.ExtractDependencies().

Something like that...

[caridy]

Could they be just abstract methods of Registry Objects? Just like we did for Module Objects?

[caridy]

This is part of #97

[caridy]

fixed by #97