Support marginHeight and marginWidth attributes

[ianobermiller]

marginHeight and marginWidth are used on iframes to set the default body margin inside the iframe.

[syranide]

I wonder if these haven't been superseded by any other property/style? They seem quite exotic (and not present in HTML5) so I can't really find any good informaton. Anyway... it seems they're available as properties even in IE8 and probably shouldn't have MUST_USE_ATTRIBUTE.

[zpao]

I was trying to find some styles that would supercede them but couldn't. We also already have frameBorder so meh. I'm losing my will to say no to things that aren't (supposedly) supported in HTML5 and we'll support arbitrary properties at some point anyway.

[zpao]

If updating these works as properties, let's just do that.

[zpao]

👍

[coveralls]

Changes Unknown when pulling 9d7467e on ianobermiller:margin-attrs into * on facebook:master*.

[aweary]

thanks for the update @coveralls