Parallax + continuousVertical: Weird Bounce

### Description
If you are using Parallax option and continuous vertical, there is a issue happening when you go up from First to Last or from Last Section to First. I believe this is just noticeable when you set the `percentage` to 100%, but that's just what I need.

### Link to isolated reproduction with no external CSS / JS
[removed link]

### Steps to reproduce it
1. Scroll Normally to the Last Section
2. Continue Scrolling until fullPage.js takes you to the first one (because continuousVertical option)
3. Notice a weird bounce in the animation. (example: http://take.ms/2NaDH)

### Versions
Desktop, macOS, Chrome 62