Change record status: 
Project: 
Introduced in branch: 
8.x
Description: 

Custom JavaScript variable: $.support.positionFixed is removed and replaced with the jQuery-provided $.support.fixedPosition.

JavaScript files in core have been updated to use jQuery's $.support.fixedPosition.

Impacts: 
Themers
Updates Done (doc team, etc.)
Online documentation: 
Not done
Theming guide: 
Not done
Module developer documentation: 
Not done
Examples project: 
Not done
Coder Review: 
Not done
Coder Upgrade: 
Not done
Other: 
Other updates done