tslint: ignore no-invalid-this for `this.timeout` in mocha clauses

tests/test-notebook/src/actions.spec.ts

@@ -37,6 +37,7 @@ describe('@jupyterlab/notebook', () => {
     let ipySession: ClientSession;
 
     before(async function() {
+      // tslint:disable-next-line:no-invalid-this
       this.timeout(60000);
       [session, ipySession] = await Promise.all([
         createClientSession(),

tests/test-notebook/src/default-toolbar.spec.ts

@@ -230,6 +230,7 @@ describe('@jupyterlab/notebook', () => {
       let panel: NotebookPanel;
 
       beforeEach(async function() {
+        // tslint:disable-next-line:no-invalid-this
         this.timeout(60000);
         context = await initNotebookContext({ startKernel: true });
         panel = NBTestUtils.createNotebookPanel(context);