Migrate textsecure to eslint

Co-authored-by: Chris Svenningsen <chris@carbonfive.com>

ts/textsecure/WebSocket.ts

@@ -0,0 +1,17 @@
+import { w3cwebsocket } from 'websocket';
+
+type ModifiedEventSource = Omit<EventSource, 'onerror'>;
+
+declare class ModifiedWebSocket extends w3cwebsocket
+  implements ModifiedEventSource {
+  withCredentials: boolean;
+
+  addEventListener: EventSource['addEventListener'];
+
+  removeEventListener: EventSource['removeEventListener'];
+
+  dispatchEvent: EventSource['dispatchEvent'];
+}
+
+export type WebSocket = ModifiedWebSocket;
+export const WebSocket = w3cwebsocket as typeof ModifiedWebSocket;