LibWeb: Implement CSSRule.parentRule and .parentStyleSheet

Both of these are supposed to be set when the CSSRule is created. The
spec is silent on setting it when a CSSRule is added to a parent. So,
this is a bit ad-hoc.

The parent rule gets set whenever a rule is added to a new parent. The
parent stylesheet gets set whenever the rule or one of its ancestors is
added to a different stylesheet. There may be some nuance there that
I'm missing, but I'm sure we'll find out quickly once we have WPT
running!

1 files changed, 6 insertions, 0 deletions

diff --git a/Userland/Libraries/LibWeb/CSS/CSSRule.idl b/Userland/Libraries/LibWeb/CSS/CSSRule.idl
index b2d416c6f8..bd40b41bd6 100644
--- a/Userland/Libraries/LibWeb/CSS/CSSRule.idl
+++ b/Userland/Libraries/LibWeb/CSS/CSSRule.idl
@@ -1,7 +1,13 @@
+#import <CSS/CSSStyleSheet.idl>
+
+[Exposed=Window]
 interface CSSRule {
 
     attribute CSSOMString cssText;
 
+    readonly attribute CSSRule? parentRule;
+    readonly attribute CSSStyleSheet? parentStyleSheet;
+
     readonly attribute unsigned short type;
 
     const unsigned short STYLE_RULE = 1;