Auto merge of #13703 - Rafagd:my_changes, r=Ms2ger

Replacing Node.rootNode for Node.getRootNode.

- Changed the specification for the Node element to reflect the new standard.
- Changed the implementation of the NodeMethod.

I'm still waiting for some answers for the questions I've posted on #13699, but I'm already doing the pull request so I can get some feedback as well.

---
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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 #13699 (github issue number if applicable).

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- [x] There are tests for these changes OR
- [ ] These changes do not require tests because _____

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components/script/dom/node.rs

@@ -1935,8 +1935,8 @@ impl NodeMethods for Node {
         }
     }
 
-    // https://dom.spec.whatwg.org/#dom-node-rootnode
-    fn RootNode(&self) -> Root<Node> {
+    // https://dom.spec.whatwg.org/#dom-node-getrootnode
+    fn GetRootNode(&self) -> Root<Node> {
         self.inclusive_ancestors().last().unwrap()
     }
 
@@ -2704,3 +2704,4 @@ impl Into<LayoutElementType> for ElementTypeId {
         }
     }
 }
+