Problem/Motivation
Bartik has several process layer functions that need to be removed or relocated, as we are removing the process layer from core.
Proposed resolution
Remove or relocate the functions.
Remaining tasks
Calls to the color module are in process_html, process_page and process_maintenance page.
Color module has to use hook_css_alter in order to work without the process function in the theme.
User interface changes
None
API changes
Color module doesn't require themes to call _color_html_alter and _color_page_alter anymore.
These two functions have been removed, and themes that still use them will break.
Related Issues
#1843650: [meta] Remove the process layer
This issue also covers #1941290: Update documentation (Remove the process layer)
