Auto merge of #14712 - KiChjang:css-keyframe-rule-style, r=Manishearth

Implement CSSKeyframeRule.style

Fixes #14636.

r? @Manishearth

<!-- Reviewable:start -->
---
This change is [<img src="https://reviewable.io/review_button.svg" height="34" align="absmiddle" alt="Reviewable"/>](https://reviewable.io/reviews/servo/servo/14712)
<!-- Reviewable:end -->

1 files changed, 19 insertions, 3 deletions

diff --git a/components/script/dom/csskeyframerule.rs b/components/script/dom/csskeyframerule.rs
index 78916d339ab..9d245d98343 100644
--- a/components/script/dom/csskeyframerule.rs
+++ b/components/script/dom/csskeyframerule.rs
@@ -2,11 +2,12 @@
  * 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::CSSKeyframeRuleBinding;
-use dom::bindings::js::Root;
-use dom::bindings::reflector::reflect_dom_object;
+use dom::bindings::codegen::Bindings::CSSKeyframeRuleBinding::{self, CSSKeyframeRuleMethods};
+use dom::bindings::js::{JS, MutNullableJS, Root};
+use dom::bindings::reflector::{DomObject, reflect_dom_object};
 use dom::bindings::str::DOMString;
 use dom::cssrule::{CSSRule, SpecificCSSRule};
+use dom::cssstyledeclaration::{CSSModificationAccess, CSSStyleDeclaration, CSSStyleOwner};
 use dom::cssstylesheet::CSSStyleSheet;
 use dom::window::Window;
 use parking_lot::RwLock;
@@ -19,6 +20,7 @@ pub struct CSSKeyframeRule {
     cssrule: CSSRule,
     #[ignore_heap_size_of = "Arc"]
     keyframerule: Arc<RwLock<Keyframe>>,
+    style_decl: MutNullableJS<CSSStyleDeclaration>,
 }
 
 impl CSSKeyframeRule {
@@ -27,6 +29,7 @@ impl CSSKeyframeRule {
         CSSKeyframeRule {
             cssrule: CSSRule::new_inherited(parent_stylesheet),
             keyframerule: keyframerule,
+            style_decl: Default::default(),
         }
     }
 
@@ -39,6 +42,19 @@ impl CSSKeyframeRule {
     }
 }
 
+impl CSSKeyframeRuleMethods for CSSKeyframeRule {
+    // https://drafts.csswg.org/css-animations/#dom-csskeyframerule-style
+    fn Style(&self) -> Root<CSSStyleDeclaration> {
+        self.style_decl.or_init(|| {
+            CSSStyleDeclaration::new(self.global().as_window(),
+                                     CSSStyleOwner::CSSRule(JS::from_ref(self.global().as_window()),
+                                                                 self.keyframerule.read().block.clone()),
+                                     None,
+                                     CSSModificationAccess::ReadWrite)
+        })
+    }
+}
+
 impl SpecificCSSRule for CSSKeyframeRule {
     fn ty(&self) -> u16 {
         use dom::bindings::codegen::Bindings::CSSRuleBinding::CSSRuleConstants;