Auto merge of #14190 - Manishearth:cssom, r=SimonSapin

Immutable CSSOM

This PR is intended to add basic support for all CSSOM interfaces, with the ability to index `document.styleSheets` and css rule lists, and serializing individual css rules. Handling individual interface methods for CSSRule subclasses can probably be done with easy/medium bugs.

Mutation safety isn't dealt with here; if the css rule list is mutated the CSSOM will be in an inconsistent state. I intend to deal with this via zero sized tokens, see https://groups.google.com/forum/#!topic/mozilla.dev.servo/AnxJoVmtMXQ .  I'll handle that when I start making the CSSOM mutable. (Getting the immutable bit landed first opens this up for easy bugs)

This doesn't really change style aside from adding an extra arc in the CSS rule list as discussed in the linked thread. So far this same design can be used by stylo as well when the time comes.

f? @SimonSapin @emilio

cc @upsuper

part of #11420
Todo:

 - [x] Stubs for rest of the CSSRule subclasses
 - [x] <s>ToCSS impls for CSSRules.</s> May make into easy bugs and stub out in this PR https://github.com/servo/servo/issues/14195
 - [x] Cache CSSStyleSheet on the relevant node

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components/script/dom/cssfontfacerule.rs

@@ -0,0 +1,50 @@
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+use dom::bindings::codegen::Bindings::CSSFontFaceRuleBinding;
+use dom::bindings::js::Root;
+use dom::bindings::reflector::reflect_dom_object;
+use dom::bindings::str::DOMString;
+use dom::cssrule::{CSSRule, SpecificCSSRule};
+use dom::cssstylesheet::CSSStyleSheet;
+use dom::window::Window;
+use parking_lot::RwLock;
+use std::sync::Arc;
+use style::font_face::FontFaceRule;
+
+#[dom_struct]
+pub struct CSSFontFaceRule {
+    cssrule: CSSRule,
+    #[ignore_heap_size_of = "Arc"]
+    fontfacerule: Arc<RwLock<FontFaceRule>>,
+}
+
+impl CSSFontFaceRule {
+    fn new_inherited(parent: &CSSStyleSheet, fontfacerule: Arc<RwLock<FontFaceRule>>) -> CSSFontFaceRule {
+        CSSFontFaceRule {
+            cssrule: CSSRule::new_inherited(parent),
+            fontfacerule: fontfacerule,
+        }
+    }
+
+    #[allow(unrooted_must_root)]
+    pub fn new(window: &Window, parent: &CSSStyleSheet,
+               fontfacerule: Arc<RwLock<FontFaceRule>>) -> Root<CSSFontFaceRule> {
+        reflect_dom_object(box CSSFontFaceRule::new_inherited(parent, fontfacerule),
+                           window,
+                           CSSFontFaceRuleBinding::Wrap)
+    }
+}
+
+impl SpecificCSSRule for CSSFontFaceRule {
+    fn ty(&self) -> u16 {
+        use dom::bindings::codegen::Bindings::CSSRuleBinding::CSSRuleConstants;
+        CSSRuleConstants::FONT_FACE_RULE
+    }
+
+    fn get_css(&self) -> DOMString {
+        // self.fontfacerule.read().to_css_string().into()
+        "".into()
+    }
+}

components/script/dom/cssgroupingrule.rs

@@ -0,0 +1,30 @@
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+use dom::bindings::codegen::Bindings::CSSGroupingRuleBinding;
+use dom::bindings::js::Root;
+use dom::bindings::reflector::reflect_dom_object;
+use dom::cssrule::CSSRule;
+use dom::cssstylesheet::CSSStyleSheet;
+use dom::window::Window;
+
+#[dom_struct]
+pub struct CSSGroupingRule {
+    cssrule: CSSRule,
+}
+
+impl CSSGroupingRule {
+    pub fn new_inherited(parent: &CSSStyleSheet) -> CSSGroupingRule {
+        CSSGroupingRule {
+            cssrule: CSSRule::new_inherited(parent),
+        }
+    }
+
+    #[allow(unrooted_must_root)]
+    pub fn new(window: &Window, parent: &CSSStyleSheet) -> Root<CSSGroupingRule> {
+        reflect_dom_object(box CSSGroupingRule::new_inherited(parent),
+                           window,
+                           CSSGroupingRuleBinding::Wrap)
+    }
+}

components/script/dom/csskeyframesrule.rs

@@ -0,0 +1,50 @@
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+use dom::bindings::codegen::Bindings::CSSKeyframesRuleBinding;
+use dom::bindings::js::Root;
+use dom::bindings::reflector::reflect_dom_object;
+use dom::bindings::str::DOMString;
+use dom::cssrule::{CSSRule, SpecificCSSRule};
+use dom::cssstylesheet::CSSStyleSheet;
+use dom::window::Window;
+use parking_lot::RwLock;
+use std::sync::Arc;
+use style::stylesheets::KeyframesRule;
+
+#[dom_struct]
+pub struct CSSKeyframesRule {
+    cssrule: CSSRule,
+    #[ignore_heap_size_of = "Arc"]
+    keyframesrule: Arc<RwLock<KeyframesRule>>,
+}
+
+impl CSSKeyframesRule {
+    fn new_inherited(parent: &CSSStyleSheet, keyframesrule: Arc<RwLock<KeyframesRule>>) -> CSSKeyframesRule {
+        CSSKeyframesRule {
+            cssrule: CSSRule::new_inherited(parent),
+            keyframesrule: keyframesrule,
+        }
+    }
+
+    #[allow(unrooted_must_root)]
+    pub fn new(window: &Window, parent: &CSSStyleSheet,
+               keyframesrule: Arc<RwLock<KeyframesRule>>) -> Root<CSSKeyframesRule> {
+        reflect_dom_object(box CSSKeyframesRule::new_inherited(parent, keyframesrule),
+                           window,
+                           CSSKeyframesRuleBinding::Wrap)
+    }
+}
+
+impl SpecificCSSRule for CSSKeyframesRule {
+    fn ty(&self) -> u16 {
+        use dom::bindings::codegen::Bindings::CSSRuleBinding::CSSRuleConstants;
+        CSSRuleConstants::KEYFRAMES_RULE
+    }
+
+    fn get_css(&self) -> DOMString {
+        // self.keyframesrule.read().to_css_string().into()
+        "".into()
+    }
+}

components/script/dom/cssmediarule.rs

@@ -0,0 +1,51 @@
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+use dom::bindings::codegen::Bindings::CSSMediaRuleBinding;
+use dom::bindings::js::Root;
+use dom::bindings::reflector::reflect_dom_object;
+use dom::bindings::str::DOMString;
+use dom::cssgroupingrule::CSSGroupingRule;
+use dom::cssrule::SpecificCSSRule;
+use dom::cssstylesheet::CSSStyleSheet;
+use dom::window::Window;
+use parking_lot::RwLock;
+use std::sync::Arc;
+use style::stylesheets::MediaRule;
+
+#[dom_struct]
+pub struct CSSMediaRule {
+    cssrule: CSSGroupingRule,
+    #[ignore_heap_size_of = "Arc"]
+    mediarule: Arc<RwLock<MediaRule>>,
+}
+
+impl CSSMediaRule {
+    fn new_inherited(parent: &CSSStyleSheet, mediarule: Arc<RwLock<MediaRule>>) -> CSSMediaRule {
+        CSSMediaRule {
+            cssrule: CSSGroupingRule::new_inherited(parent),
+            mediarule: mediarule,
+        }
+    }
+
+    #[allow(unrooted_must_root)]
+    pub fn new(window: &Window, parent: &CSSStyleSheet,
+               mediarule: Arc<RwLock<MediaRule>>) -> Root<CSSMediaRule> {
+        reflect_dom_object(box CSSMediaRule::new_inherited(parent, mediarule),
+                           window,
+                           CSSMediaRuleBinding::Wrap)
+    }
+}
+
+impl SpecificCSSRule for CSSMediaRule {
+    fn ty(&self) -> u16 {
+        use dom::bindings::codegen::Bindings::CSSRuleBinding::CSSRuleConstants;
+        CSSRuleConstants::MEDIA_RULE
+    }
+
+    fn get_css(&self) -> DOMString {
+        // self.mediarule.read().to_css_string().into()
+        "".into()
+    }
+}

components/script/dom/cssnamespacerule.rs

@@ -0,0 +1,50 @@
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+use dom::bindings::codegen::Bindings::CSSNamespaceRuleBinding;
+use dom::bindings::js::Root;
+use dom::bindings::reflector::reflect_dom_object;
+use dom::bindings::str::DOMString;
+use dom::cssrule::{CSSRule, SpecificCSSRule};
+use dom::cssstylesheet::CSSStyleSheet;
+use dom::window::Window;
+use parking_lot::RwLock;
+use std::sync::Arc;
+use style::stylesheets::NamespaceRule;
+
+#[dom_struct]
+pub struct CSSNamespaceRule {
+    cssrule: CSSRule,
+    #[ignore_heap_size_of = "Arc"]
+    namespacerule: Arc<RwLock<NamespaceRule>>,
+}
+
+impl CSSNamespaceRule {
+    fn new_inherited(parent: &CSSStyleSheet, namespacerule: Arc<RwLock<NamespaceRule>>) -> CSSNamespaceRule {
+        CSSNamespaceRule {
+            cssrule: CSSRule::new_inherited(parent),
+            namespacerule: namespacerule,
+        }
+    }
+
+    #[allow(unrooted_must_root)]
+    pub fn new(window: &Window, parent: &CSSStyleSheet,
+               namespacerule: Arc<RwLock<NamespaceRule>>) -> Root<CSSNamespaceRule> {
+        reflect_dom_object(box CSSNamespaceRule::new_inherited(parent, namespacerule),
+                           window,
+                           CSSNamespaceRuleBinding::Wrap)
+    }
+}
+
+impl SpecificCSSRule for CSSNamespaceRule {
+    fn ty(&self) -> u16 {
+        use dom::bindings::codegen::Bindings::CSSRuleBinding::CSSRuleConstants;
+        CSSRuleConstants::NAMESPACE_RULE
+    }
+
+    fn get_css(&self) -> DOMString {
+        // self.namespacerule.read().to_css_string().into()
+        "".into()
+    }
+}

components/script/dom/cssrule.rs

@@ -0,0 +1,103 @@
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+use dom::bindings::codegen::Bindings::CSSRuleBinding;
+use dom::bindings::codegen::Bindings::CSSRuleBinding::CSSRuleMethods;
+use dom::bindings::inheritance::Castable;
+use dom::bindings::js::{JS, MutNullableHeap, Root};
+use dom::bindings::reflector::{Reflector, reflect_dom_object};
+use dom::bindings::str::DOMString;
+use dom::cssfontfacerule::CSSFontFaceRule;
+use dom::csskeyframesrule::CSSKeyframesRule;
+use dom::cssmediarule::CSSMediaRule;
+use dom::cssnamespacerule::CSSNamespaceRule;
+use dom::cssstylerule::CSSStyleRule;
+use dom::cssstylesheet::CSSStyleSheet;
+use dom::cssviewportrule::CSSViewportRule;
+use dom::window::Window;
+use style::stylesheets::CssRule as StyleCssRule;
+
+
+#[dom_struct]
+pub struct CSSRule {
+    reflector_: Reflector,
+    parent: MutNullableHeap<JS<CSSStyleSheet>>,
+}
+
+impl CSSRule {
+    #[allow(unrooted_must_root)]
+    pub fn new_inherited(parent: &CSSStyleSheet) -> CSSRule {
+        CSSRule {
+            reflector_: Reflector::new(),
+            parent: MutNullableHeap::new(Some(parent)),
+        }
+    }
+
+    #[allow(unrooted_must_root)]
+    pub fn new(window: &Window, parent: &CSSStyleSheet) -> Root<CSSRule> {
+        reflect_dom_object(box CSSRule::new_inherited(parent),
+                           window,
+                           CSSRuleBinding::Wrap)
+    }
+
+    pub fn as_specific(&self) -> &SpecificCSSRule {
+        if let Some(rule) = self.downcast::<CSSStyleRule>() {
+            rule as &SpecificCSSRule
+        } else if let Some(rule) = self.downcast::<CSSFontFaceRule>() {
+            rule as &SpecificCSSRule
+        } else if let Some(rule) = self.downcast::<CSSKeyframesRule>() {
+            rule as &SpecificCSSRule
+        } else if let Some(rule) = self.downcast::<CSSMediaRule>() {
+            rule as &SpecificCSSRule
+        } else if let Some(rule) = self.downcast::<CSSNamespaceRule>() {
+            rule as &SpecificCSSRule
+        } else if let Some(rule) = self.downcast::<CSSViewportRule>() {
+            rule as &SpecificCSSRule
+        } else {
+            unreachable!()
+        }
+    }
+
+    // Given a StyleCssRule, create a new instance of a derived class of
+    // CSSRule based on which rule it is
+    pub fn new_specific(window: &Window, parent: &CSSStyleSheet,
+                        rule: StyleCssRule) -> Root<CSSRule> {
+        // be sure to update the match in as_specific when this is updated
+        match rule {
+            StyleCssRule::Style(s) => Root::upcast(CSSStyleRule::new(window, parent, s)),
+            StyleCssRule::FontFace(s) => Root::upcast(CSSFontFaceRule::new(window, parent, s)),
+            StyleCssRule::Keyframes(s) => Root::upcast(CSSKeyframesRule::new(window, parent, s)),
+            StyleCssRule::Media(s) => Root::upcast(CSSMediaRule::new(window, parent, s)),
+            StyleCssRule::Namespace(s) => Root::upcast(CSSNamespaceRule::new(window, parent, s)),
+            StyleCssRule::Viewport(s) => Root::upcast(CSSViewportRule::new(window, parent, s)),
+        }
+    }
+}
+
+impl CSSRuleMethods for CSSRule {
+    // https://drafts.csswg.org/cssom/#dom-cssrule-type
+    fn Type(&self) -> u16 {
+        self.as_specific().ty()
+    }
+
+    // https://drafts.csswg.org/cssom/#dom-cssrule-parentstylesheet
+    fn GetParentStyleSheet(&self) -> Option<Root<CSSStyleSheet>> {
+        self.parent.get()
+    }
+
+    // https://drafts.csswg.org/cssom/#dom-cssrule-csstext
+    fn CssText(&self) -> DOMString {
+        self.as_specific().get_css()
+    }
+
+    // https://drafts.csswg.org/cssom/#dom-cssrule-csstext
+    fn SetCssText(&self, _: DOMString) {
+        // do nothing
+    }
+}
+
+pub trait SpecificCSSRule {
+    fn ty(&self) -> u16;
+    fn get_css(&self) -> DOMString;
+}

components/script/dom/cssrulelist.rs

@@ -0,0 +1,67 @@
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+use dom::bindings::codegen::Bindings::CSSRuleListBinding;
+use dom::bindings::codegen::Bindings::CSSRuleListBinding::CSSRuleListMethods;
+use dom::bindings::js::{JS, MutNullableHeap, Root};
+use dom::bindings::reflector::{Reflectable, Reflector, reflect_dom_object};
+use dom::cssrule::CSSRule;
+use dom::cssstylesheet::CSSStyleSheet;
+use dom::window::Window;
+use style::stylesheets::CssRules;
+
+no_jsmanaged_fields!(CssRules);
+
+#[dom_struct]
+pub struct CSSRuleList {
+    reflector_: Reflector,
+    sheet: JS<CSSStyleSheet>,
+    #[ignore_heap_size_of = "Arc"]
+    rules: CssRules,
+    dom_rules: Vec<MutNullableHeap<JS<CSSRule>>>
+}
+
+impl CSSRuleList {
+    #[allow(unrooted_must_root)]
+    pub fn new_inherited(sheet: &CSSStyleSheet, rules: CssRules) -> CSSRuleList {
+        let dom_rules = rules.0.read().iter().map(|_| MutNullableHeap::new(None)).collect();
+        CSSRuleList {
+            reflector_: Reflector::new(),
+            sheet: JS::from_ref(sheet),
+            rules: rules,
+            dom_rules: dom_rules,
+        }
+    }
+
+    #[allow(unrooted_must_root)]
+    pub fn new(window: &Window, sheet: &CSSStyleSheet, rules: CssRules) -> Root<CSSRuleList> {
+        reflect_dom_object(box CSSRuleList::new_inherited(sheet, rules),
+                           window,
+                           CSSRuleListBinding::Wrap)
+    }
+}
+
+impl CSSRuleListMethods for CSSRuleList {
+    // https://drafts.csswg.org/cssom/#ref-for-dom-cssrulelist-item-1
+    fn Item(&self, idx: u32) -> Option<Root<CSSRule>> {
+        self.dom_rules.get(idx as usize).map(|rule| {
+            rule.or_init(|| {
+                CSSRule::new_specific(self.global().as_window(),
+                                     &self.sheet,
+                                     self.rules.0.read()[idx as usize].clone())
+            })
+        })
+    }
+
+    // https://drafts.csswg.org/cssom/#dom-cssrulelist-length
+    fn Length(&self) -> u32 {
+        self.dom_rules.len() as u32
+    }
+
+    // check-tidy: no specs after this line
+    fn IndexedGetter(&self, index: u32) -> Option<Root<CSSRule>> {
+        self.Item(index)
+    }
+}
+

components/script/dom/cssstylerule.rs

@@ -0,0 +1,50 @@
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+use dom::bindings::codegen::Bindings::CSSStyleRuleBinding;
+use dom::bindings::js::Root;
+use dom::bindings::reflector::reflect_dom_object;
+use dom::bindings::str::DOMString;
+use dom::cssrule::{CSSRule, SpecificCSSRule};
+use dom::cssstylesheet::CSSStyleSheet;
+use dom::window::Window;
+use parking_lot::RwLock;
+use std::sync::Arc;
+use style::stylesheets::StyleRule;
+use style_traits::ToCss;
+
+#[dom_struct]
+pub struct CSSStyleRule {
+    cssrule: CSSRule,
+    #[ignore_heap_size_of = "Arc"]
+    stylerule: Arc<RwLock<StyleRule>>,
+}
+
+impl CSSStyleRule {
+    fn new_inherited(parent: &CSSStyleSheet, stylerule: Arc<RwLock<StyleRule>>) -> CSSStyleRule {
+        CSSStyleRule {
+            cssrule: CSSRule::new_inherited(parent),
+            stylerule: stylerule,
+        }
+    }
+
+    #[allow(unrooted_must_root)]
+    pub fn new(window: &Window, parent: &CSSStyleSheet,
+               stylerule: Arc<RwLock<StyleRule>>) -> Root<CSSStyleRule> {
+        reflect_dom_object(box CSSStyleRule::new_inherited(parent, stylerule),
+                           window,
+                           CSSStyleRuleBinding::Wrap)
+    }
+}
+
+impl SpecificCSSRule for CSSStyleRule {
+    fn ty(&self) -> u16 {
+        use dom::bindings::codegen::Bindings::CSSRuleBinding::CSSRuleConstants;
+        CSSRuleConstants::STYLE_RULE
+    }
+
+    fn get_css(&self) -> DOMString {
+        self.stylerule.read().to_css_string().into()
+    }
+}

components/script/dom/cssstylesheet.rs

@@ -0,0 +1,51 @@
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+use dom::bindings::codegen::Bindings::CSSStyleSheetBinding;
+use dom::bindings::codegen::Bindings::CSSStyleSheetBinding::CSSStyleSheetMethods;
+use dom::bindings::js::{JS, Root, MutNullableHeap};
+use dom::bindings::reflector::{reflect_dom_object, Reflectable};
+use dom::bindings::str::DOMString;
+use dom::cssrulelist::CSSRuleList;
+use dom::stylesheet::StyleSheet;
+use dom::window::Window;
+use std::sync::Arc;
+use style::stylesheets::Stylesheet as StyleStyleSheet;
+
+#[dom_struct]
+pub struct CSSStyleSheet {
+    stylesheet: StyleSheet,
+    rulelist: MutNullableHeap<JS<CSSRuleList>>,
+    #[ignore_heap_size_of = "Arc"]
+    style_stylesheet: Arc<StyleStyleSheet>,
+}
+
+impl CSSStyleSheet {
+    fn new_inherited(type_: DOMString, href: Option<DOMString>,
+                     title: Option<DOMString>, stylesheet: Arc<StyleStyleSheet>) -> CSSStyleSheet {
+        CSSStyleSheet {
+            stylesheet: StyleSheet::new_inherited(type_, href, title),
+            rulelist: MutNullableHeap::new(None),
+            style_stylesheet: stylesheet,
+        }
+    }
+
+    #[allow(unrooted_must_root)]
+    pub fn new(window: &Window, type_: DOMString,
+               href: Option<DOMString>,
+               title: Option<DOMString>,
+               stylesheet: Arc<StyleStyleSheet>) -> Root<CSSStyleSheet> {
+        reflect_dom_object(box CSSStyleSheet::new_inherited(type_, href, title, stylesheet),
+                           window,
+                           CSSStyleSheetBinding::Wrap)
+    }
+}
+
+impl CSSStyleSheetMethods for CSSStyleSheet {
+    // https://drafts.csswg.org/cssom/#dom-cssstylesheet-cssrules
+    fn CssRules(&self) -> Root<CSSRuleList> {
+        self.rulelist.or_init(|| CSSRuleList::new(self.global().as_window(), self, self.style_stylesheet.rules.clone()))
+    }
+}
+

components/script/dom/cssviewportrule.rs

@@ -0,0 +1,50 @@
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+use dom::bindings::codegen::Bindings::CSSViewportRuleBinding;
+use dom::bindings::js::Root;
+use dom::bindings::reflector::reflect_dom_object;
+use dom::bindings::str::DOMString;
+use dom::cssrule::{CSSRule, SpecificCSSRule};
+use dom::cssstylesheet::CSSStyleSheet;
+use dom::window::Window;
+use parking_lot::RwLock;
+use std::sync::Arc;
+use style::viewport::ViewportRule;
+
+#[dom_struct]
+pub struct CSSViewportRule {
+    cssrule: CSSRule,
+    #[ignore_heap_size_of = "Arc"]
+    viewportrule: Arc<RwLock<ViewportRule>>,
+}
+
+impl CSSViewportRule {
+    fn new_inherited(parent: &CSSStyleSheet, viewportrule: Arc<RwLock<ViewportRule>>) -> CSSViewportRule {
+        CSSViewportRule {
+            cssrule: CSSRule::new_inherited(parent),
+            viewportrule: viewportrule,
+        }
+    }
+
+    #[allow(unrooted_must_root)]
+    pub fn new(window: &Window, parent: &CSSStyleSheet,
+               viewportrule: Arc<RwLock<ViewportRule>>) -> Root<CSSViewportRule> {
+        reflect_dom_object(box CSSViewportRule::new_inherited(parent, viewportrule),
+                           window,
+                           CSSViewportRuleBinding::Wrap)
+    }
+}
+
+impl SpecificCSSRule for CSSViewportRule {
+    fn ty(&self) -> u16 {
+        use dom::bindings::codegen::Bindings::CSSRuleBinding::CSSRuleConstants;
+        CSSRuleConstants::VIEWPORT_RULE
+    }
+
+    fn get_css(&self) -> DOMString {
+        // self.viewportrule.read().to_css_string().into()
+        "".into()
+    }
+}

components/script/dom/document.rs

@@ -59,10 +59,7 @@ use dom::htmlheadelement::HTMLHeadElement;
 use dom::htmlhtmlelement::HTMLHtmlElement;
 use dom::htmliframeelement::HTMLIFrameElement;
 use dom::htmlimageelement::HTMLImageElement;
-use dom::htmllinkelement::HTMLLinkElement;
-use dom::htmlmetaelement::HTMLMetaElement;
 use dom::htmlscriptelement::HTMLScriptElement;
-use dom::htmlstyleelement::HTMLStyleElement;
 use dom::htmltitleelement::HTMLTitleElement;
 use dom::keyboardevent::KeyboardEvent;
 use dom::location::Location;
@@ -152,10 +149,10 @@ enum ParserBlockedByScript {
 
 #[derive(JSTraceable, HeapSizeOf)]
 #[must_root]
-struct StylesheetInDocument {
-    node: JS<Node>,
+pub struct StylesheetInDocument {
+    pub node: JS<Node>,
     #[ignore_heap_size_of = "Arc"]
-    stylesheet: Arc<Stylesheet>,
+    pub stylesheet: Arc<Stylesheet>,
 }
 
 // https://dom.spec.whatwg.org/#document
@@ -189,6 +186,7 @@ pub struct Document {
     stylesheets: DOMRefCell<Option<Vec<StylesheetInDocument>>>,
     /// Whether the list of stylesheets has changed since the last reflow was triggered.
     stylesheets_changed_since_reflow: Cell<bool>,
+    stylesheet_list: MutNullableHeap<JS<StyleSheetList>>,
     ready_state: Cell<DocumentReadyState>,
     /// Whether the DOMContentLoaded event has already been dispatched.
     domcontentloaded_dispatched: Cell<bool>,
@@ -1811,6 +1809,7 @@ impl Document {
             applets: Default::default(),
             stylesheets: DOMRefCell::new(None),
             stylesheets_changed_since_reflow: Cell::new(false),
+            stylesheet_list: MutNullableHeap::new(None),
             ready_state: Cell::new(ready_state),
             domcontentloaded_dispatched: Cell::new(domcontentloaded_dispatched),
             possibly_focused: Default::default(),
@@ -1910,35 +1909,37 @@ impl Document {
         self.GetDocumentElement().and_then(Root::downcast)
     }
 
+    // Ensure that the stylesheets vector is populated
+    fn ensure_stylesheets(&self) {
+        let mut stylesheets = self.stylesheets.borrow_mut();
+        if stylesheets.is_none() {
+            *stylesheets = Some(self.upcast::<Node>()
+                .traverse_preorder()
+                .filter_map(|node| {
+                    node.get_stylesheet()
+                        .map(|stylesheet| StylesheetInDocument {
+                        node: JS::from_ref(&*node),
+                        stylesheet: stylesheet,
+                    })
+                })
+                .collect());
+        };
+    }
+
     /// Returns the list of stylesheets associated with nodes in the document.
     pub fn stylesheets(&self) -> Vec<Arc<Stylesheet>> {
-        {
-            let mut stylesheets = self.stylesheets.borrow_mut();
-            if stylesheets.is_none() {
-                *stylesheets = Some(self.upcast::<Node>()
-                    .traverse_preorder()
-                    .filter_map(|node| {
-                        if let Some(node) = node.downcast::<HTMLStyleElement>() {
-                            node.get_stylesheet()
-                        } else if let Some(node) = node.downcast::<HTMLLinkElement>() {
-                            node.get_stylesheet()
-                        } else if let Some(node) = node.downcast::<HTMLMetaElement>() {
-                            node.get_stylesheet()
-                        } else {
-                            None
-                        }.map(|stylesheet| StylesheetInDocument {
-                            node: JS::from_ref(&*node),
-                            stylesheet: stylesheet
-                        })
-                    })
-                    .collect());
-            };
-        }
+        self.ensure_stylesheets();
         self.stylesheets.borrow().as_ref().unwrap().iter()
                         .map(|s| s.stylesheet.clone())
                         .collect()
     }
 
+    pub fn with_style_sheets_in_document<F, T>(&self, mut f: F) -> T
+            where F: FnMut(&[StylesheetInDocument]) -> T {
+        self.ensure_stylesheets();
+        f(&self.stylesheets.borrow().as_ref().unwrap())
+    }
+
     /// https://html.spec.whatwg.org/multipage/#appropriate-template-contents-owner-document
     pub fn appropriate_template_contents_owner_document(&self) -> Root<Document> {
         self.appropriate_template_contents_owner_document.or_init(|| {
@@ -2038,7 +2039,7 @@ impl Element {
 impl DocumentMethods for Document {
     // https://drafts.csswg.org/cssom/#dom-document-stylesheets
     fn StyleSheets(&self) -> Root<StyleSheetList> {
-        StyleSheetList::new(&self.window, JS::from_ref(&self))
+        self.stylesheet_list.or_init(|| StyleSheetList::new(&self.window, JS::from_ref(&self)))
     }
 
     // https://dom.spec.whatwg.org/#dom-document-implementation

components/script/dom/htmllinkelement.rs

@@ -14,6 +14,7 @@ use dom::bindings::js::{JS, MutNullableHeap, Root, RootedReference};
 use dom::bindings::refcounted::Trusted;
 use dom::bindings::reflector::Reflectable;
 use dom::bindings::str::DOMString;
+use dom::cssstylesheet::CSSStyleSheet;
 use dom::document::Document;
 use dom::domtokenlist::DOMTokenList;
 use dom::element::{AttributeMutation, Element, ElementCreator};
@@ -56,6 +57,7 @@ pub struct HTMLLinkElement {
     rel_list: MutNullableHeap<JS<DOMTokenList>>,
     #[ignore_heap_size_of = "Arc"]
     stylesheet: DOMRefCell<Option<Arc<Stylesheet>>>,
+    cssom_stylesheet: MutNullableHeap<JS<CSSStyleSheet>>,
 
     /// https://html.spec.whatwg.org/multipage/#a-style-sheet-that-is-blocking-scripts
     parser_inserted: Cell<bool>,
@@ -69,6 +71,7 @@ impl HTMLLinkElement {
             rel_list: Default::default(),
             parser_inserted: Cell::new(creator == ElementCreator::ParserCreated),
             stylesheet: DOMRefCell::new(None),
+            cssom_stylesheet: MutNullableHeap::new(None),
         }
     }
 
@@ -85,6 +88,18 @@ impl HTMLLinkElement {
     pub fn get_stylesheet(&self) -> Option<Arc<Stylesheet>> {
         self.stylesheet.borrow().clone()
     }
+
+    pub fn get_cssom_stylesheet(&self) -> Option<Root<CSSStyleSheet>> {
+        self.get_stylesheet().map(|sheet| {
+            self.cssom_stylesheet.or_init(|| {
+                CSSStyleSheet::new(&window_from_node(self),
+                                   "text/css".into(),
+                                   None, // todo handle location
+                                   None, // todo handle title
+                                   sheet)
+            })
+        })
+    }
 }
 
 fn get_attr(element: &Element, local_name: &LocalName) -> Option<String> {

components/script/dom/htmlmetaelement.rs

@@ -8,13 +8,14 @@ use dom::bindings::codegen::Bindings::HTMLMetaElementBinding;
 use dom::bindings::codegen::Bindings::HTMLMetaElementBinding::HTMLMetaElementMethods;
 use dom::bindings::codegen::Bindings::NodeBinding::NodeMethods;
 use dom::bindings::inheritance::Castable;
-use dom::bindings::js::{Root, RootedReference};
+use dom::bindings::js::{JS, MutNullableHeap, Root, RootedReference};
 use dom::bindings::str::DOMString;
+use dom::cssstylesheet::CSSStyleSheet;
 use dom::document::Document;
 use dom::element::{AttributeMutation, Element};
 use dom::htmlelement::HTMLElement;
 use dom::htmlheadelement::HTMLHeadElement;
-use dom::node::{Node, UnbindContext, document_from_node};
+use dom::node::{Node, UnbindContext, document_from_node, window_from_node};
 use dom::virtualmethods::VirtualMethods;
 use html5ever_atoms::LocalName;
 use parking_lot::RwLock;
@@ -30,6 +31,7 @@ pub struct HTMLMetaElement {
     htmlelement: HTMLElement,
     #[ignore_heap_size_of = "Arc"]
     stylesheet: DOMRefCell<Option<Arc<Stylesheet>>>,
+    cssom_stylesheet: MutNullableHeap<JS<CSSStyleSheet>>,
 }
 
 impl HTMLMetaElement {
@@ -39,6 +41,7 @@ impl HTMLMetaElement {
         HTMLMetaElement {
             htmlelement: HTMLElement::new_inherited(local_name, prefix, document),
             stylesheet: DOMRefCell::new(None),
+            cssom_stylesheet: MutNullableHeap::new(None),
         }
     }
 
@@ -55,6 +58,18 @@ impl HTMLMetaElement {
         self.stylesheet.borrow().clone()
     }
 
+    pub fn get_cssom_stylesheet(&self) -> Option<Root<CSSStyleSheet>> {
+        self.get_stylesheet().map(|sheet| {
+            self.cssom_stylesheet.or_init(|| {
+                CSSStyleSheet::new(&window_from_node(self),
+                                   "text/css".into(),
+                                   None, // todo handle location
+                                   None, // todo handle title
+                                   sheet)
+            })
+        })
+    }
+
     fn process_attributes(&self) {
         let element = self.upcast::<Element>();
         if let Some(name) = element.get_attribute(&ns!(), &local_name!("name")).r() {
@@ -81,7 +96,7 @@ impl HTMLMetaElement {
             if !content.is_empty() {
                 if let Some(translated_rule) = ViewportRule::from_meta(&**content) {
                     *self.stylesheet.borrow_mut() = Some(Arc::new(Stylesheet {
-                        rules: vec![CssRule::Viewport(Arc::new(RwLock::new(translated_rule)))],
+                        rules: vec![CssRule::Viewport(Arc::new(RwLock::new(translated_rule)))].into(),
                         origin: Origin::Author,
                         media: Default::default(),
                         // Viewport constraints are always recomputed on resize; they don't need to

components/script/dom/htmlstyleelement.rs

@@ -7,8 +7,9 @@ use dom::bindings::cell::DOMRefCell;
 use dom::bindings::codegen::Bindings::HTMLStyleElementBinding;
 use dom::bindings::codegen::Bindings::NodeBinding::NodeMethods;
 use dom::bindings::inheritance::Castable;
-use dom::bindings::js::Root;
+use dom::bindings::js::{JS, MutNullableHeap, Root};
 use dom::bindings::str::DOMString;
+use dom::cssstylesheet::CSSStyleSheet;
 use dom::document::Document;
 use dom::element::Element;
 use dom::htmlelement::HTMLElement;
@@ -26,6 +27,7 @@ pub struct HTMLStyleElement {
     htmlelement: HTMLElement,
     #[ignore_heap_size_of = "Arc"]
     stylesheet: DOMRefCell<Option<Arc<Stylesheet>>>,
+    cssom_stylesheet: MutNullableHeap<JS<CSSStyleSheet>>,
 }
 
 impl HTMLStyleElement {
@@ -35,6 +37,7 @@ impl HTMLStyleElement {
         HTMLStyleElement {
             htmlelement: HTMLElement::new_inherited(local_name, prefix, document),
             stylesheet: DOMRefCell::new(None),
+            cssom_stylesheet: MutNullableHeap::new(None),
         }
     }
 
@@ -77,6 +80,18 @@ impl HTMLStyleElement {
     pub fn get_stylesheet(&self) -> Option<Arc<Stylesheet>> {
         self.stylesheet.borrow().clone()
     }
+
+    pub fn get_cssom_stylesheet(&self) -> Option<Root<CSSStyleSheet>> {
+        self.get_stylesheet().map(|sheet| {
+            self.cssom_stylesheet.or_init(|| {
+                CSSStyleSheet::new(&window_from_node(self),
+                                   "text/css".into(),
+                                   None, // todo handle location
+                                   None, // todo handle title
+                                   sheet)
+            })
+        })
+    }
 }
 
 impl VirtualMethods for HTMLStyleElement {

components/script/dom/mod.rs

@@ -242,7 +242,17 @@ pub mod comment;
 pub mod console;
 pub mod crypto;
 pub mod css;
+pub mod cssfontfacerule;
+pub mod cssgroupingrule;
+pub mod csskeyframesrule;
+pub mod cssmediarule;
+pub mod cssnamespacerule;
+pub mod cssrule;
+pub mod cssrulelist;
 pub mod cssstyledeclaration;
+pub mod cssstylerule;
+pub mod cssstylesheet;
+pub mod cssviewportrule;
 pub mod customevent;
 pub mod dedicatedworkerglobalscope;
 pub mod document;

components/script/dom/node.rs

@@ -30,6 +30,7 @@ use dom::bindings::reflector::{Reflectable, reflect_dom_object};
 use dom::bindings::str::{DOMString, USVString};
 use dom::bindings::xmlname::namespace_from_domstring;
 use dom::characterdata::{CharacterData, LayoutCharacterDataHelpers};
+use dom::cssstylesheet::CSSStyleSheet;
 use dom::document::{Document, DocumentSource, IsHTMLDocument};
 use dom::documentfragment::DocumentFragment;
 use dom::documenttype::DocumentType;
@@ -43,6 +44,9 @@ use dom::htmlelement::HTMLElement;
 use dom::htmliframeelement::{HTMLIFrameElement, HTMLIFrameElementLayoutMethods};
 use dom::htmlimageelement::{HTMLImageElement, LayoutHTMLImageElementHelpers};
 use dom::htmlinputelement::{HTMLInputElement, LayoutHTMLInputElementHelpers};
+use dom::htmllinkelement::HTMLLinkElement;
+use dom::htmlmetaelement::HTMLMetaElement;
+use dom::htmlstyleelement::HTMLStyleElement;
 use dom::htmltextareaelement::{HTMLTextAreaElement, LayoutHTMLTextAreaElementHelpers};
 use dom::nodelist::NodeList;
 use dom::processinginstruction::ProcessingInstruction;
@@ -76,8 +80,10 @@ use std::default::Default;
 use std::iter;
 use std::mem;
 use std::ops::Range;
+use std::sync::Arc;
 use style::dom::OpaqueNode;
 use style::selector_impl::ServoSelectorImpl;
+use style::stylesheets::Stylesheet;
 use style::thread_state;
 use url::Url;
 use uuid::Uuid;
@@ -901,6 +907,30 @@ impl Node {
         element.upcast::<Node>().remove_self();
         Ok(())
     }
+
+    pub fn get_stylesheet(&self) -> Option<Arc<Stylesheet>> {
+        if let Some(node) = self.downcast::<HTMLStyleElement>() {
+            node.get_stylesheet()
+        } else if let Some(node) = self.downcast::<HTMLLinkElement>() {
+            node.get_stylesheet()
+        } else if let Some(node) = self.downcast::<HTMLMetaElement>() {
+            node.get_stylesheet()
+        } else {
+            None
+        }
+    }
+
+    pub fn get_cssom_stylesheet(&self) -> Option<Root<CSSStyleSheet>> {
+        if let Some(node) = self.downcast::<HTMLStyleElement>() {
+            node.get_cssom_stylesheet()
+        } else if let Some(node) = self.downcast::<HTMLLinkElement>() {
+            node.get_cssom_stylesheet()
+        } else if let Some(node) = self.downcast::<HTMLMetaElement>() {
+            node.get_cssom_stylesheet()
+        } else {
+            None
+        }
+    }
 }
 
 

components/script/dom/stylesheet.rs

@@ -20,7 +20,7 @@ pub struct StyleSheet {
 
 impl StyleSheet {
     #[allow(unrooted_must_root)]
-    fn new_inherited(type_: DOMString, href: Option<DOMString>, title: Option<DOMString>) -> StyleSheet {
+    pub fn new_inherited(type_: DOMString, href: Option<DOMString>, title: Option<DOMString>) -> StyleSheet {
         StyleSheet {
             reflector_: Reflector::new(),
             type_: type_,

components/script/dom/stylesheetlist.rs

@@ -35,13 +35,18 @@ impl StyleSheetList {
 impl StyleSheetListMethods for StyleSheetList {
     // https://drafts.csswg.org/cssom/#dom-stylesheetlist-length
     fn Length(&self) -> u32 {
-       self.document.stylesheets().len() as u32
+       self.document.with_style_sheets_in_document(|s| s.len() as u32)
     }
 
     // https://drafts.csswg.org/cssom/#dom-stylesheetlist-item
-    fn Item(&self, _index: u32) -> Option<Root<StyleSheet>> {
-        None
-        //TODO Create a new StyleSheet object and return it
+    fn Item(&self, index: u32) -> Option<Root<StyleSheet>> {
+        // XXXManishearth this  doesn't handle the origin clean flag
+        // and is a cors vulnerability
+        self.document.with_style_sheets_in_document(|sheets| {
+            sheets.get(index as usize)
+                  .and_then(|sheet| sheet.node.get_cssom_stylesheet())
+                  .map(Root::upcast)
+        })
     }
 
     // check-tidy: no specs after this line

components/script/dom/webidls/CSS.webidl

@@ -6,7 +6,7 @@
  * http://dev.w3.org/csswg/cssom/#the-css-interface
  */
 
-[Abstract, Exposed=(Window,Worker)]
+[Abstract, Exposed=Window]
 interface CSS {
   [Throws]
   static DOMString escape(DOMString ident);

components/script/dom/webidls/CSSFontFaceRule.webidl

@@ -0,0 +1,17 @@
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+// https://drafts.csswg.org/css-fonts/#cssfontfacerule
+[Exposed=Window]
+interface CSSFontFaceRule : CSSRule {
+  // attribute DOMString family;
+  // attribute DOMString src;
+  // attribute DOMString style;
+  // attribute DOMString weight;
+  // attribute DOMString stretch;
+  // attribute DOMString unicodeRange;
+  // attribute DOMString variant;
+  // attribute DOMString featureSettings;
+};
+

components/script/dom/webidls/CSSGroupingRule.webidl

@@ -0,0 +1,12 @@
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+// https://drafts.csswg.org/cssom/#the-cssgroupingrule-interface
+[Exposed=Window]
+interface CSSGroupingRule : CSSRule {
+  // [SameObject] readonly attribute CSSRuleList cssRules;
+  // unsigned long insertRule(DOMString rule, unsigned long index);
+  // void deleteRule(unsigned long index);
+};
+

components/script/dom/webidls/CSSKeyframesRule.webidl

@@ -0,0 +1,14 @@
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+// https://drafts.csswg.org/css-animations/#interface-csskeyframesrule
+[Exposed=Window]
+interface CSSKeyframesRule : CSSRule {
+  //          attribute DOMString   name;
+  // readonly attribute CSSRuleList cssRules;
+
+  // void            appendRule(DOMString rule);
+  // void            deleteRule(DOMString select);
+  // CSSKeyframeRule? findRule(DOMString select);
+};

components/script/dom/webidls/CSSMediaRule.webidl

@@ -0,0 +1,9 @@
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+// https://drafts.csswg.org/cssom/#the-cssmediarule-interface
+[Exposed=Window]
+interface CSSMediaRule : CSSGroupingRule {
+  // [SameObject, PutForwards=mediaText] readonly attribute MediaList media;
+};

components/script/dom/webidls/CSSNamespaceRule.webidl

@@ -0,0 +1,10 @@
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+// https://drafts.csswg.org/cssom/#the-cssnamespacerule-interface
+[Exposed=Window]
+interface CSSNamespaceRule : CSSRule {
+  // readonly attribute DOMString namespaceURI;
+  // readonly attribute DOMString prefix;
+};

components/script/dom/webidls/CSSRule.webidl

@@ -0,0 +1,33 @@
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+// https://drafts.csswg.org/cssom/#the-cssrule-interface
+[Exposed=Window]
+interface CSSRule {
+  const unsigned short STYLE_RULE = 1;
+  const unsigned short CHARSET_RULE = 2; // historical
+  const unsigned short IMPORT_RULE = 3;
+  const unsigned short MEDIA_RULE = 4;
+  const unsigned short FONT_FACE_RULE = 5;
+  const unsigned short PAGE_RULE = 6;
+  const unsigned short MARGIN_RULE = 9;
+  const unsigned short NAMESPACE_RULE = 10;
+
+  readonly attribute unsigned short type;
+  attribute DOMString cssText;
+  // readonly attribute CSSRule? parentRule;
+  readonly attribute CSSStyleSheet? parentStyleSheet;
+};
+
+// https://drafts.csswg.org/css-animations/#interface-cssrule-idl
+partial interface CSSRule {
+    const unsigned short KEYFRAMES_RULE = 7;
+    const unsigned short KEYFRAME_RULE = 8;
+};
+
+// https://drafts.csswg.org/css-device-adapt/#css-rule-interface
+partial interface CSSRule {
+    const unsigned short VIEWPORT_RULE = 15;
+};
+

components/script/dom/webidls/CSSRuleList.webidl

@@ -0,0 +1,11 @@
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+// https://drafts.csswg.org/cssom/#cssrulelist
+// [LegacyArrayClass]
+[Exposed=Window]
+interface CSSRuleList {
+  getter CSSRule? item(unsigned long index);
+  readonly attribute unsigned long length;
+};

components/script/dom/webidls/CSSStyleDeclaration.webidl

@@ -8,7 +8,7 @@
  * Copyright © 2013 W3C® (MIT, ERCIM, Keio, Beihang), All Rights Reserved.
  */
 
-[Exposed=(Window,Worker)]
+[Exposed=(Window, Worker)]
 interface CSSStyleDeclaration {
   [SetterThrows]
            attribute DOMString cssText;

components/script/dom/webidls/CSSStyleRule.webidl

@@ -0,0 +1,10 @@
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+// https://drafts.csswg.org/cssom/#the-cssstylerule-interface
+[Exposed=Window]
+interface CSSStyleRule : CSSRule {
+  // attribute DOMString selectorText;
+  // [SameObject, PutForwards=cssText] readonly attribute CSSStyleDeclaration style;
+};

components/script/dom/webidls/CSSStyleSheet.webidl

@@ -0,0 +1,12 @@
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+// https://drafts.csswg.org/cssom/#the-cssstylesheet-interface
+[Exposed=Window]
+interface CSSStyleSheet : StyleSheet {
+  // readonly attribute CSSRule? ownerRule;
+  [SameObject] readonly attribute CSSRuleList cssRules;
+  // unsigned long insertRule(DOMString rule, unsigned long index);
+  // void deleteRule(unsigned long index);
+};

components/script/dom/webidls/CSSViewportRule.webidl

@@ -0,0 +1,9 @@
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+// https://drafts.csswg.org/css-device-adapt/#css-viewport-rule-interface
+[Exposed=Window]
+interface CSSViewportRule : CSSRule {
+    // readonly attribute CSSStyleDeclaration style;
+};

components/script/dom/webidls/StyleSheet.webidl

@@ -3,7 +3,7 @@
  * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
 
 // https://drafts.csswg.org/cssom/#the-stylesheet-interface
-[Exposed=(Window,Worker)]
+[Exposed=Window]
 interface StyleSheet {
   readonly attribute DOMString type_;
   readonly attribute DOMString? href;

components/script/dom/webidls/StyleSheetList.webidl

@@ -4,7 +4,7 @@
 
 // https://drafts.csswg.org/cssom/#the-stylesheetlist-interface
 // [ArrayClass]
-[Exposed=(Window,Worker)]
+[Exposed=Window]
 interface StyleSheetList {
   getter StyleSheet? item(unsigned long index);
   readonly attribute unsigned long length;