Black border (left, right, bottom) added to body after lightbox closes on iOS Safari

[mkhatib]

Not sure if this is already in prod/canary. But it's in current master.

Repro:

1. Run local server
2. navigate to everything.amp.max.html example
3. Locate the Open Lightbox button
4. Click it
5. Click close dialog
6. Notice a visible black border appearing.

Computed styles for body changes as follow:

/* Before Opening Dialog */
border-top-color: rgba(0, 0, 0, 0);
border-top-style: solid;
border-top-width: 0px;
height: 628px;
width: 414px;

/* After Opening Dialog */
border-bottom-style: none;
border-left-style: none;
border-right-style: none;
border-top-color: rgba(0, 0, 0, 0);
border-top-style: none;
border-top-width: 0px;
height: 628px;
width: 414px;

/* After closing dialog */
border-bottom-style: solid;
border-left-style: solid;
border-right-style: solid;
border-top-color: rgba(0, 0, 0, 0);
border-top-style: solid;
border-top-width: 0px;

Seen on iOS 9.2

[erwinmombay]

@mkhatib can you checkout 1474310684773 and check if this bug is there?