safari: survey-text submit causes page to refresh

[jodeleeuw]

This is fixed by adding onsubmit="return false;" but I don't know if this has other consequences that need to be considered.

[nabsul]

I was able to reproduce this bug on Edge as well. Doesn't happen in Chrome.

[nabsul]

The correct way to fix this is to add a call to event.preventDefault() in the submit function of survey-text.

I checked out other trials such as survey-multi-choice and they already have this in their code, so I think it was just missed by mistake.

@jodeleeuw It looks like they'll have this fixed in 6.0.6, but you can make the fix yourself as shown in the pull request that I've submitted.

[jodeleeuw]

fixed in #613