Separated proposed changes to extension semantics from PR #386 and use TypeError, per @jyasskin

Per discussions on the 22-Mar-18 WG call, these semantic changes previously part of the mbj-registries-and-extensions branch proposed as pull request #386<> are now in the separate branch mbj-extension-semantics. Thanks to @jyasskin<> for suggesting the use of the TypeError exception.

See pull request

                                                       -- Mike

Received on Thursday, 23 March 2017 22:09:59 UTC