Editor: Cannot scroll inside fast preview on iOS

[kriskarkoski]

Steps to reproduce:

1. Go to https://wordpress.com/post and start a new post
2. Add a title and some content
3. Tap the "Actions" button
4. Tap the "Preview" button
5. Try to scroll around to see the whole post in the fast preview screen

Result: cannot scroll or see the whole post in the fast preview.

^{Seen at https://horizon.wordpress.com/post/design5279.wordpress.com/9320 using Safari iOS 9.1 on iPhone 6}

Is the preview set to the correct default when viewing on mobile? When I tap the Preview button to see a fast preview, it looks oversized (see screenshot above) and when I tap the external preview button, the preview looks normal:

^{Seen at https://design5279.wordpress.com/?p=9320&preview=true&iframe=true using Safari iOS 9.1 on iPhone 6}

[nylen]

Reported in 271879-chat (iPad on iOS 9.1, Safari 9) and confirmed in iOS Simulator (iPad on iOS 8.2):

[aduth]

Fixed by #3376