In  issue 611982  we are adding a feature policy to prevent iframes from blocking vertical scroll, however there are sites where horizontal scrolling is the main / major scrolling axis.

For example, the top stories news carousel on google search results conceptually is horizontally scrolling with snap points at the top-level through frames which scroll vertically. Similarly, many application UI's often adopt horizontal scrolling as the primary axis through screens of various components.

I think we may want to add a similar feature policy for horizontal scrolling, either:
A. in combination with vertical scrolling,
B. as an alternative to vertical scrolling, or
C. as automatic detection of the primary scrolling axis.