SwipeableDrawer demos broken on iOS

[mikew]

The swipeable drawers component demos are (severely) broken on iOS.

• This is a v1.x issue (v0.x is no longer maintained).
• I have searched the issues of this repository and believe that this is not a duplicate.

Expected Behavior

Current Behavior

Multiple drawers visible all the time, overlapping drawers, some scroll with the page.

Steps to Reproduce (for bugs)

1. Visit https://material-ui.com/demos/drawers/ on iOS.
   https://gfycat.com/AcceptableLinearFlicker

Context

Your Environment

• iOS 11.3.1

[mikew]

In case anyone comes to this issue before the docs are fixed: both the Drawer and SwipeableDrawer components work beautifully on iOS.

[Forfold]

Can confirm that with a drawer open, the content behind the div will scroll with your finger as you swipe open/close. I don't think it used to do this

[oliviertassinari]

I was able to track down the root of the issue. It's a SSR mismatch on the demos from this line:
https://github.com/mui-org/material-ui/blob/a2c69371bec6629995b67f080b3a5808cf4e07bb/packages/material-ui/src/SwipeableDrawer/SwipeableDrawer.js#L451-L452

I'm fixing it.

[oliviertassinari]

@mikew Thanks for reporting the issue.