Auto merge of #17259 - jyc:new-CSSStyleSheet, r=emilio

Force HTMLStyleElement to create a new CSSStyleSheet when re-parsing.

- [X] `./mach build -d` does not report any errors
- [X] `./mach test-tidy` does not report any errors

- [X] These changes do not require tests because I'm pushing to find out what test results this changes; this is part of a series of PRs to fix bug #17182

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components/script/dom/htmlstyleelement.rs

@@ -111,6 +111,7 @@ impl HTMLStyleElement {
 
         win.layout_chan().send(Msg::AddStylesheet(sheet.clone())).unwrap();
         *self.stylesheet.borrow_mut() = Some(sheet);
+        self.cssom_stylesheet.set(None);
         doc.invalidate_stylesheets();
     }