Fix js-flipper tests (#3297)

Summary: Pull Request resolved: https://github.com/facebook/flipper/pull/3297

Reviewed By: passy

Differential Revision: D33619287

fbshipit-source-id: 7e9dc595c999e9c8b61329f96adba6e45a1dfa50

js/js-flipper/jest.config.js

@@ -8,7 +8,7 @@
  */
 
 module.exports = {
-  preset: "ts-jest",
+  preset: 'ts-jest',
   clearMocks: true,
   coverageReporters: ['json-summary', 'lcov', 'html'],
   testMatch: ['**/**.spec.(js|jsx|ts|tsx)'],