According to the HTML specification, the `size` attribute of an input
element must be a valid non-negative integer greater than zero. If the
value is invalid or set to `0`, the default size of `20` should be used.
This small change fixes one issue identified in
https://wpt.live/html/rendering/widgets/input-text-size.html
The WPT test suite was also automatically imported.
In the case where we had a preferred aspect ratio and a natural height
but no natural width, we'd get into ping-ponging infinite recursion by
trying to find the width to resolve the height to resolve the width to
resolve the height...
