Upstream HTML Rendering section's monkey patches to CSS

[zcorpan]

See whatwg/html#5462 (comment)

HTML special-cases handling of the 'line-height' property for the input element, for web compat. To make it more discoverable for implementers, it would be good to specify this in the definition of the 'line-height' property directly. Though maybe HTML can still say which elements exercise the special behavior.

There's more stuff like this in HTML. For example the margin collapsing quirk, fieldset's layout model, ignoring 'overflow' on marquee, to name a few.