Auto merge of #11182 - mrmiywj:add-attribute-mutated, r=KiChjang

htmlanchorelement getter work before href setting is called

Thank you for contributing to Servo! Please replace each `[ ]` by `[X]` when the step is complete, and replace `__` with appropriate data:
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- [X] `./mach test-tidy` does not report any errors
- [X] These changes fix #10876  (github issue number if applicable).

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components/script/dom/htmlanchorelement.rs

@@ -71,7 +71,6 @@ impl HTMLAnchorElement {
     fn reinitialize_url(&self) {
         // Step 1.
         match *self.url.borrow() {
-            None => return,
             Some(ref url) if url.scheme() == "blob" && url.cannot_be_a_base() => return,
             _ => (),
         }