Full height general page not sized correctly

Issue Summary

When creating a general page that should be 100% high, it renders with slightly larger height causing a scroll bar to appear. 

For additional context, see https://community.developer.atlassian.com/t/generalpage-doesnt-get-proper-height-in-chrome/46688.

Steps to Reproduce

1. Create an app declaring a general page such that it should be full height. See https://glitch.com/edit/#!/dx-general-page-app?path=page.html%3A51%3A0 and https://dx-general-page-app.glitch.me/connect.json.
2. Install the app.
3. Visit the general page created by the app.
4. Observe the rendered results.

Expected Results

The height of the general page is such that it fills the page space provided, but no more.

Actual Results

An additional scroll bar appears.

Workaround

In order to fix it:

const scrollHeight = document.body.scrollHeight;
AP.resize('100%', `${scrollHeight.toString()}px`);
AP.sizeToParent();