Merge pull request #10591 from electron/disable-app-importcertificate-tests

disable flaky app.importCertificate and select-client-certificate tests

spec/api-app-spec.js

@@ -236,7 +236,7 @@ describe('app module', function () {
     })
   })
 
-  describe('app.importCertificate', function () {
+  xdescribe('app.importCertificate', function () {
     if (process.platform !== 'linux') return
 
     this.timeout(120000)
@@ -434,7 +434,7 @@ describe('app module', function () {
     })
   })
 
-  describe('select-client-certificate event', function () {
+  xdescribe('select-client-certificate event', function () {
     let w = null
 
     beforeEach(function () {