Auto merge of #25272 - pshaughn:domexception_inherits_tostring, r=Manishearth

DOMException now inherits its Javascript toString from Error

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stringifier is out of the DOMException IDL, and Stringifier(&self) is moved into the main body of DOMException where it can continue to be called internally.

---
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- [X] `./mach test-tidy` does not report any errors
- [X] These changes fix #25042

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- [X] There are tests for these changes

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components/script/dom/webidls/DOMException.webidl

@@ -47,6 +47,4 @@ interface DOMException {
 
   // A custom message set by the thrower.
   readonly attribute DOMString message;
-
-  stringifier;
 };