add nonpassive event modifier to mouse wheel and touchstart event lis…

[ronkeiser]

Problem

Chrome complains of non-passive event listener violations if certain listeners are not explicitly marked as non-passive. It's kind of dumb:

Solution

We can get rid of this warning by adding the nonpassive event modifier like so:

 on:wheel|nonpassive|preventDefault={onWheel}

This PR adds two modifiers to clean up the console warnings when using svelte-easy-crop in Chrome.

[ValentinH]

Thanks for this PR. It was published as https://github.com/ValentinH/svelte-easy-crop/releases/tag/v2.0.4