Bug 1691075 - [devtools] Fix error in startup/worker.js. r=bomsy.

Differential Revision: https://phabricator.services.mozilla.com/D104793

devtools/server/startup/worker.js

@@ -43,7 +43,7 @@ this.rpc = function(method, ...params) {
       })
     );
   });
-};
+}.bind(this);
 
 loadSubScript("resource://devtools/shared/worker/loader.js");