[BUG] PointerEvent float properties

[rickyvetter]

In practice all of the positional properties (clientX/Y, etc) on pointerEvents are floats, not ints (at least in latest Chrome). In the Dom_html they inherit from mouseEvent, which describes all of these values as ints. In wasm this fails with a cast error (and in javacript obviously there is a loss of precision in the number).

I think the right fix is to update the types, ideally before the float/int breaking change in js_of_ocaml so that folks can migrate both at the same time. Maybe a closer audit of these values would be good to ensure we aren't missing more?

[vouillon]

Indeed, the type of these MouseEvent properties has been changed from int to float.
https://www.w3.org/TR/cssom-view-1/#extensions-to-the-mouseevent-interface

That would not be a bad thing to audit and modernize the Js_of_ocaml library.