Auto merge of #10761 - amarant:Node-isSameNode, r=Ms2ger

Implements Node::isSameNode

Fixes #10746

I adapted the tests from dom/nodes/Node-isEqualNode.html
should I also add ones for xhtml too like here : dom/nodes/Node-isEqualNode-xhtml.xhtml ?

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components/script/dom/node.rs

@@ -2230,6 +2230,14 @@ impl NodeMethods for Node {
         }
     }
 
+    // https://dom.spec.whatwg.org/#dom-node-issamenode
+    fn IsSameNode(&self, otherNode: Option<&Node>) -> bool {
+        match otherNode {
+            Some(node) => self == node,
+            None => false,
+        }
+    }
+
     // https://dom.spec.whatwg.org/#dom-node-comparedocumentposition
     fn CompareDocumentPosition(&self, other: &Node) -> u16 {
         if self == other {

components/script/dom/webidls/Node.webidl

@@ -58,6 +58,8 @@ interface Node : EventTarget {
   Node cloneNode(optional boolean deep = false);
   [Pure]
   boolean isEqualNode(Node? node);
+  [Pure]
+  boolean isSameNode(Node? otherNode); // historical alias of ===
 
   const unsigned short DOCUMENT_POSITION_DISCONNECTED = 0x01;
   const unsigned short DOCUMENT_POSITION_PRECEDING = 0x02;