Test flake: Catalog numbers should accept valid values

[php-coder]

Catalog numbers should accept valid values :: Verify that fields w... | FAIL |
Several failures occurred:
1) You may only interact with visible elements
Build info: version: '2.53.1', revision: 'a36b8b1cd5757287168e54b817830adce9b0158d', time: '2016-06-30 19:26:09'
System info: host: 'testing-gce-4b24f957-f37f-4fd6-9334-5b356068136d', ip: '127.0.1.1', os.name: 'Linux', os.arch: 'amd64', os.version: '3.13.0-103-generic', java.version: '1.8.0_111'
Driver info: driver.version: unknown

2) You may only interact with visible elements
Build info: version: '2.53.1', revision: 'a36b8b1cd5757287168e54b817830adce9b0158d', time: '2016-06-30 19:26:09'
System info: host: 'testing-gce-4b24f957-f37f-4fd6-9334-5b356068136d', ip: '127.0.1.1', os.name: 'Linux', os.arch: 'amd64', os.version: '3.13.0-103-generic', java.version: '1.8.0_111'
Driver info: driver.version: unknown

Seen here: https://travis-ci.org/php-coder/mystamps/jobs/214819545

[php-coder]

Another one: https://travis-ci.org/php-coder/mystamps/jobs/215326049