Move eslint-disable no-undef to a global comment

Summary:
Switch the only `// eslint-disable no-undef` to defined the global instead so that the new babel-eslint-no-undef compile time check doesn't need to understand inline eslint comments.

Changelog: [Internal]

Reviewed By: cpojer

Differential Revision: D18644590

fbshipit-source-id: ac9c6da3a5e63b285b5e1dde210613b5d893641b

RNTester/js/examples/XHR/XHRExampleAbortController.js

@@ -19,8 +19,7 @@ class XHRExampleAbortController extends React.Component<{...}, {...}> {
 
   _submit(abortDelay) {
     clearTimeout(this._timeout);
-    // eslint-disable-next-line no-undef
-    const abortController = new AbortController();
+    const abortController = new global.AbortController();
     fetch('https://facebook.github.io/react-native/', {
       signal: abortController.signal,
     })