Fix the Node interface

Author: falsandtru

baselines/dom.generated.d.ts

@@ -8732,18 +8732,18 @@ interface Node extends EventTarget {
     readonly attributes: NamedNodeMap;
     readonly baseURI: string | null;
     readonly childNodes: NodeList;
-    readonly firstChild: Node;
-    readonly lastChild: Node;
+    readonly firstChild: Node | null;
+    readonly lastChild: Node | null;
     readonly localName: string | null;
     readonly namespaceURI: string | null;
-    readonly nextSibling: Node;
+    readonly nextSibling: Node | null;
     readonly nodeName: string;
     readonly nodeType: number;
     nodeValue: string | null;
     readonly ownerDocument: Document;
-    readonly parentElement: HTMLElement;
-    readonly parentNode: Node;
-    readonly previousSibling: Node;
+    readonly parentElement: HTMLElement | null;
+    readonly parentNode: Node | null;
+    readonly previousSibling: Node | null;
     textContent: string | null;
     appendChild(newChild: Node): Node;
     cloneNode(deep?: boolean): Node;

inputfiles/overridingTypes.json

@@ -845,5 +845,47 @@
         "interface": "History",
         "name": "replaceState",
         "signatures": ["replaceState(data: any, title: string, url?: string | null): void"]
+    },
+    {
+        "kind": "property",
+        "interface": "Node",
+        "readonly": true,
+        "name": "firstChild",
+        "type": "Node | null"
+    },
+    {
+        "kind": "property",
+        "interface": "Node",
+        "readonly": true,
+        "name": "lastChild",
+        "type": "Node | null"
+    },
+    {
+        "kind": "property",
+        "interface": "Node",
+        "readonly": true,
+        "name": "nextSibling",
+        "type": "Node | null"
+    },
+    {
+        "kind": "property",
+        "interface": "Node",
+        "readonly": true,
+        "name": "previousSibling",
+        "type": "Node | null"
+    },
+    {
+        "kind": "property",
+        "interface": "Node",
+        "readonly": true,
+        "name": "parentNode",
+        "type": "Node | null"
+    },
+    {
+        "kind": "property",
+        "interface": "Node",
+        "readonly": true,
+        "name": "parentElement",
+        "type": "HTMLElement | null"
     }
  ]