Auto merge of #14646 - canaltinova:origin-clean, r=jdm

Support origins in CSSOM stylesheets

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I still need to pass the origin clean flag to constructors. `style::stylesheets::Stylesheet` has an origin field but I don't think that's relevant.
I can get href in htmllinkelement.rs like this:
```rust
let element = self.upcast::<Element>();
let href = element.get_string_attribute(&local_name!("href"));
```
But I'm not sure how to proceed after here.
@Manishearth any opinions?

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- [X] `./mach build -d` does not report any errors
- [X] `./mach test-tidy` does not report any errors
- [X] These changes fix #14327 (github issue number if applicable).

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- [X] There are tests for these changes

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components/script/dom/webidls/CSSStyleSheet.webidl

@@ -6,7 +6,7 @@
 [Exposed=Window]
 interface CSSStyleSheet : StyleSheet {
   // readonly attribute CSSRule? ownerRule;
-  [SameObject] readonly attribute CSSRuleList cssRules;
+  [Throws, SameObject] readonly attribute CSSRuleList cssRules;
   [Throws] unsigned long insertRule(DOMString rule, unsigned long index);
   [Throws] void deleteRule(unsigned long index);
 };