#CT-7653: Remove scrollbar from iFrames that extend past lenght of page

@pheuter I want to get your feedback on my changes before we merge. See comments.
Probably should have made a constant to be more descriptive. The 100 was empirically determined based on mobile testing. We don't want to set the height exactly to the window height, cause it still gets cut off for modals on mobile, so an additional padding provided the desired UI.

Commenting this out means modals will probably suck again on mobile.