[w3c/webauthn] 931b46: Make create() and get() abortable (#544)

  Branch: refs/heads/master
  Home:   https://github.com/w3c/webauthn
  Commit: 931b46eece69f5d780ce4b317e3a377a3a67f85c
      https://github.com/w3c/webauthn/commit/931b46eece69f5d780ce4b317e3a377a3a67f85c
  Author: Angelo Liao <huliao@microsoft.com>
  Date:   2017-11-08 (Wed, 08 Nov 2017)

  Changed paths:
    M index.bs

  Log Message:
  -----------
  Make create() and get() abortable  (#544)

* do not call authenticatorMakeCredential() with separate |rpId| fixes #466

* credID returned by authnrGetAssn() is optional if allowCreds has exactly 1 member fixes #472

* fixup global object reference per domenic, improves #472

* indent 4.1.4 step 18et al to clarify relation to prior step

* fix line indent

* do not call authenticatorMakeCredential() with separate |rpId| fixes #466

* credID returned by authnrGetAssn() is optional if allowCreds has exactly 1 member fixes #472

* fixup global object reference per domenic, improves #472

* indent 4.1.4 step 18et al to clarify relation to prior step

* fix line indent

* post rebase-on-master, fix dangling MakeCredentialOptions

* fix error in resolving rebase conflicts

* further rebase conflict resolution error fixups

* convert switch steps to colon-denotation

* tag 'while'

* primary changes for improving #472 mostly complete

* further issue #472 cleanups

* del 'cancel the timer' from #creatCredential fixes #535

* polish constructResultantCredentialCallback method description

* marked authenticator model section as non-normative

* marked relying party operation section as non-normative

* fix proper subset tweak

* Added abort signal object and steps to webauthn

* fixed a minor issue with linking

* add minor edits to focus on the main things

* getting the blank line correct

* Added a example section to explain how abort should be used

* fix up example

* committing before computer dies

* updated grammars of the example based on feedback

* update example text

* Updated with the section on switching tab; complete the PR

* minor tweak

* finished polishing the spec

* whoops one leftover

* finally figured out how to remove last two linking errors

* take out abortsignal from extension; edit promise rejection