SpecificResource is not defined in the active context for Ranges

[azaroth42]

Discovered by Steve Baskauf at Vanderbilt, the use of SpecificResource as an items entry in a Range is not covered by the context.

SpecificResource is defined only in the Annotation context, which is imported using class-scoped context definitions for AnnotationCollection, AnnotationPage and Annotation. So when processing the Range, it iterates through the items only with the Presentation API context active.

Fix is to define SpecificResource within Range and have its context import the web annotation context definitions. Thankfully, the context definition is not normative so we can change without a version bump to the spec.

Screenshots of the issue from Steve, reposted with permission: