Remove unused code (#209)

* Remove unused code

* Update snapshots

Author: martinRenou

packages/xeus/src/interfaces.ts

@@ -42,11 +42,6 @@ export interface IXeusWorkerKernel extends IWorkerKernel {
    */
   processWorkerMessage(msg: any): void;
 
-  /**
-   * Register a callback for handling messages from the worker.
-   */
-  registerCallback(callback: (msg: any) => void): void;
-
   /**
    * Whether the kernel is ready.
    * @returns a promise that resolves when the kernel is ready.

packages/xeus/src/worker.ts

@@ -232,16 +232,7 @@ export class XeusRemoteKernel {
     kernelReady(1);
   }
 
-  /**
-   * Register the callback function to send messages from the worker back to the main thread.
-   * @param callback the callback to register
-   */
-  registerCallback(callback: (msg: any) => void): void {
-    this._sendWorkerMessage = callback;
-  }
-
   private _logger: XeusWorkerLogger;
-  protected _sendWorkerMessage: (msg: any) => void = () => {};
 }
 
 export namespace XeusRemoteKernel {