Hook up shared process sorta

packages/vscode/src/fill/dom.ts

@@ -0,0 +1,19 @@
+// Firefox has no implementation of toElement.
+if (!("toElement" in MouseEvent.prototype)) {
+	Object.defineProperty(MouseEvent.prototype, "toElement", {
+		get: function (): EventTarget | null {
+			// @ts-ignore
+			const event = this as MouseEvent;
+			switch (event.type) {
+				case "mouseup":
+				case "focusin":
+				case "mousenter":
+				case "mouseover":
+				case "dragenter":
+					return event.target;
+				default:
+					return event.relatedTarget;
+			}
+		},
+	});
+}