fly-in preset display issue

`fly-in` preset should start fully off screen.
Currently they're appearing in screen before transition start.
This is apparent in desktop mode when screen is higher than 1180px.

Preview link, when on page 5 this is visible on page 6
be sure to be in desktop mode with screen higher than 1180px:
https://webstoriesinteractivity-beta.web.app/animals-polls.html

This may be a problem with the distance is calculation.
When scaling the viewport the element comes in and out.

The offsetY calculation may be the culprit. It might need to be a responsive value in desktop mode.
https://github.com/ampproject/amphtml/blob/master/extensions/amp-story/1.0/animation-presets.js#L145-L152

All other `fly-in` presets might need to be double checked also.

Example of element in view, it should be off screen:

Element is coming in and out in top right of next page when scaling window:

cc @ampproject/wg-stories @hongcatlover