servo: Merge #20083 - enable css paint api and remove forked duplicates (from yurket:19840_enable_css_pain_api_and_remove_forked_duplicates); r=jdm

1) Move paintWorklet from "Window" to "CSS" according to new specification;
2) Enable WPT css-paint-api tests from upstream and remove forked duplicates from mozilla folder

- [X] `./mach build -d` does not report any errors
- [X] `./mach test-tidy` does not report any errors
- [X] These changes fix #19840
- [X] These changes do not require tests because the change was made in tests it-selves

Source-Repo: https://github.com/servo/servo
Source-Revision: a0e340d68f5a51d61a69b0bc16f543d3cef54597

servo/components/script/dom/css.rs

@@ -6,8 +6,10 @@ use cssparser::{Parser, ParserInput, serialize_identifier};
 use dom::bindings::codegen::Bindings::WindowBinding::WindowBinding::WindowMethods;
 use dom::bindings::error::Fallible;
 use dom::bindings::reflector::Reflector;
+use dom::bindings::root::DomRoot;
 use dom::bindings::str::DOMString;
 use dom::window::Window;
+use dom::worklet::Worklet;
 use dom_struct::dom_struct;
 use style::context::QuirksMode;
 use style::parser::ParserContext;
@@ -63,4 +65,9 @@ impl CSS {
             false
         }
     }
+
+    /// <https://drafts.css-houdini.org/css-paint-api-1/#paint-worklet>
+    pub fn PaintWorklet(win: &Window) -> DomRoot<Worklet> {
+        win.paint_worklet()
+    }
 }