Problem/Motivation
jQuery UI Dialog and Autocomplete both need to be shimmed: #2158943: Replace jQuery UI dialog with supported library or polyfill#3076171: Provide a new library to replace jQuery UI autocomplete
Both features use jQuery UI position(). Instead of including position() in the scope of either of those issues, it should be scoped to its own issue as all of these jUI shim issues are already quite large, and this can easily get its own scope.
Steps to reproduce
Proposed resolution
Create a custom version of jQuery UI position in /misc, to be used instead of the position within jQuery UI. It will be modified to meet Drupal coding standards and so that it extends jQuery instead of jQuery UI. This only requires changing assumptions regarding the presence of $.ui to non-UI jQuery.
Because jQuery UI position does not have any fixed dependencies on other parts of jQuery UI, making a custom version for use in core is acceptably maintainable.
