don't call method of destroyed webContents

Author: steven nguyen

lib/worker.js

@@ -45,10 +45,6 @@ const averageTracker = new AverageTracker({limit: operationCountLimit});
 const childPidsById = new Map();
 
 const destroyRenderer = () => {
-  if (!managerWebContents.isDestroyed()) {
-    managerWebContents.removeListener('crashed', destroyRenderer);
-    managerWebContents.removeListener('destroyed', destroyRenderer);
-  }
   const win = remote.BrowserWindow.fromWebContents(remote.getCurrentWebContents());
   if (win && !win.isDestroyed()) {
     win.destroy();