Have background, border and gradient modules
for calculation functions.
Use shorter names for functions that are qualified
by the module name like `border::radii`.
Use push_item and push_iter to add items to WebRender.
Implement corner clipping.
Remove PixelFormat from WebrenderImageInfo.
Use WebRender text shadow.
Remove MallocSizeOf and Deserialize for DL items.
Closes#19649, #19680, #19802
Add an IndexableText structure for text queries.
Instead of linear search for a node this now uses a HashMap.
Remove the now irrelevant fields from TextDisplayItem.
Move display_list_builder.rs and webrender_helpers.rs
along with the new file to components/layout/display_list/
Remove apparently unused IdType enum.
Only variant used was OverflowClip.
See #19676
