STR:
- Enable VerticalFormControlsEnabled
- Visit one of these URLs:

data:text/html,<input type="search" style="writing-mode: vertical-lr">

or

data:text/html,<input type="number" style="writing-mode: vertical-lr">

or

data:text/html,<input type="password" style="writing-mode: vertical-lr">

- Type in the input until it overflows

AR:
- The number spinner overflows out of the input
- When you type even more on a page that has overflow, the page starts scrolling as you type (try it on https://bugs.webkit.org/attachment.cgi?id=463717)

Tests should be added for both of these items, both can probably be WPT:
- First one could be tested using a reftest
- Second one could test that the scroll position is stable