[Checkbox without ripple] When clicking checkbox without ripple, ripple circle appears for a brief moment

- material-design-lite#1.2.1
- latest Chrome 53.0.2785.143 (64-bit)

When clicking on other site element and then clicking on MDL checkbox, most times a ripple circle appears for a split second even when not using ripple class. It shouldn't appear in any case other than actually using ripple effect.

I determined that this is caused by `.mdl-checkbox__focus-helper` and `.mdl-switch__focus-helper` as when I've hidden these elements the problem disappeared.

For now I'm fixing this with `display: none !important` (because I don't plan to use ripple checkboxes or switches in any part of my site) but it should be handled properly in the library.

EDIT: Confirmed the same bug for switch.