Auto merge of #22743 - ferjm:shadowdom, r=emilio

Partial ShadowDOM support

This is just an early WIP, not to take it very seriously yet.

- [X] `./mach build -d` does not report any errors
- [X] `./mach test-tidy` does not report any errors
- [x] These changes fix #22719
- [x] There are tests for these changes

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1 files changed, 62 insertions, 7 deletions

diff --git a/components/script/dom/stylesheetlist.rs b/components/script/dom/stylesheetlist.rs
index c1c5c0b2d5f..236f1c9cd9a 100644
--- a/components/script/dom/stylesheetlist.rs
+++ b/components/script/dom/stylesheetlist.rs
@@ -6,30 +6,85 @@ use crate::dom::bindings::codegen::Bindings::StyleSheetListBinding;
 use crate::dom::bindings::codegen::Bindings::StyleSheetListBinding::StyleSheetListMethods;
 use crate::dom::bindings::reflector::{reflect_dom_object, Reflector};
 use crate::dom::bindings::root::{Dom, DomRoot};
+use crate::dom::cssstylesheet::CSSStyleSheet;
 use crate::dom::document::Document;
+use crate::dom::element::Element;
+use crate::dom::shadowroot::ShadowRoot;
 use crate::dom::stylesheet::StyleSheet;
 use crate::dom::window::Window;
 use dom_struct::dom_struct;
+use servo_arc::Arc;
+use style::stylesheets::Stylesheet;
+
+#[must_root]
+#[derive(JSTraceable, MallocSizeOf)]
+pub enum StyleSheetListOwner {
+    Document(Dom<Document>),
+    ShadowRoot(Dom<ShadowRoot>),
+}
+
+impl StyleSheetListOwner {
+    pub fn stylesheet_count(&self) -> usize {
+        match *self {
+            StyleSheetListOwner::Document(ref doc) => doc.stylesheet_count(),
+            StyleSheetListOwner::ShadowRoot(ref shadow_root) => shadow_root.stylesheet_count(),
+        }
+    }
+
+    pub fn stylesheet_at(&self, index: usize) -> Option<DomRoot<CSSStyleSheet>> {
+        match *self {
+            StyleSheetListOwner::Document(ref doc) => doc.stylesheet_at(index),
+            StyleSheetListOwner::ShadowRoot(ref shadow_root) => shadow_root.stylesheet_at(index),
+        }
+    }
+
+    pub fn add_stylesheet(&self, owner: &Element, sheet: Arc<Stylesheet>) {
+        match *self {
+            StyleSheetListOwner::Document(ref doc) => doc.add_stylesheet(owner, sheet),
+            StyleSheetListOwner::ShadowRoot(ref shadow_root) => {
+                shadow_root.add_stylesheet(owner, sheet)
+            },
+        }
+    }
+
+    pub fn remove_stylesheet(&self, owner: &Element, s: &Arc<Stylesheet>) {
+        match *self {
+            StyleSheetListOwner::Document(ref doc) => doc.remove_stylesheet(owner, s),
+            StyleSheetListOwner::ShadowRoot(ref shadow_root) => {
+                shadow_root.remove_stylesheet(owner, s)
+            },
+        }
+    }
+
+    pub fn invalidate_stylesheets(&self) {
+        match *self {
+            StyleSheetListOwner::Document(ref doc) => doc.invalidate_stylesheets(),
+            StyleSheetListOwner::ShadowRoot(ref shadow_root) => {
+                shadow_root.invalidate_stylesheets()
+            },
+        }
+    }
+}
 
 #[dom_struct]
 pub struct StyleSheetList {
     reflector_: Reflector,
-    document: Dom<Document>,
+    document_or_shadow_root: StyleSheetListOwner,
 }
 
 impl StyleSheetList {
     #[allow(unrooted_must_root)]
-    fn new_inherited(doc: Dom<Document>) -> StyleSheetList {
+    fn new_inherited(doc_or_sr: StyleSheetListOwner) -> StyleSheetList {
         StyleSheetList {
             reflector_: Reflector::new(),
-            document: doc,
+            document_or_shadow_root: doc_or_sr,
         }
     }
 
     #[allow(unrooted_must_root)]
-    pub fn new(window: &Window, document: Dom<Document>) -> DomRoot<StyleSheetList> {
+    pub fn new(window: &Window, doc_or_sr: StyleSheetListOwner) -> DomRoot<StyleSheetList> {
         reflect_dom_object(
-            Box::new(StyleSheetList::new_inherited(document)),
+            Box::new(StyleSheetList::new_inherited(doc_or_sr)),
             window,
             StyleSheetListBinding::Wrap,
         )
@@ -39,14 +94,14 @@ impl StyleSheetList {
 impl StyleSheetListMethods for StyleSheetList {
     // https://drafts.csswg.org/cssom/#dom-stylesheetlist-length
     fn Length(&self) -> u32 {
-        self.document.stylesheet_count() as u32
+        self.document_or_shadow_root.stylesheet_count() as u32
     }
 
     // https://drafts.csswg.org/cssom/#dom-stylesheetlist-item
     fn Item(&self, index: u32) -> Option<DomRoot<StyleSheet>> {
         // XXXManishearth this  doesn't handle the origin clean flag and is a
         // cors vulnerability
-        self.document
+        self.document_or_shadow_root
             .stylesheet_at(index as usize)
             .map(DomRoot::upcast)
     }