fix remote setInterval flake (#12263)

spec/node-spec.js

@@ -184,11 +184,15 @@ describe('node feature', () => {
     describe('setInterval called under Chromium event loop in browser process', () => {
       it('can be scheduled in time', (done) => {
         let interval = null
+        let clearing = false
         const clear = () => {
-          if (interval === null) {
+          if (interval === null || clearing) {
             return
           }
+          // interval might trigger while clearing (remote is slow sometimes)
+          clearing = true
           remote.getGlobal('clearInterval')(interval)
+          clearing = false
           interval = null
           done()
         }