swift234

runtime: Use -debugQuickLookObject to get text or image quick look objects.

In response to feedback from the Xcode team, change the 'IDERepresentable' type from a protocol into an enum with a limited set of tags, starting with 'Text' and 'Image' for now. In the ObjC mirror, if the ObjC object has a -debugQuickLookObject method, use it to get an object we can try to map to the enum.

Swift SVN r14632