[cssom] Table row resolved width and height.

See https://bugzilla.mozilla.org/show_bug.cgi?id=1590837 / https://github.com/jquery/jquery/issues/4529.

In the following test-case:

<table style="border-collapse: separate; border-spacing: 0; background: #baffc9"><tbody>
	<tr id="tr" style="margin: 0; border: 10px solid black; padding: 0">
		<td style="margin: 0; border: 0; padding: 0; height: 42px; width: 42px;"></td>
	</tr>
</tbody></table>
    <div id="result"></div>
<script>
var result = document.getElementById('result');
var tr = document.getElementById('tr');
result.innerHTML = getComputedStyle(tr).width;
</script>

Gecko reports 42px. Blink/WebKit report 22px. EdgeHTML reported auto.

width and height on table rows have no effect, so I think Edge was right on this one, and table rows should behave the same way non-replaced inlines behave, and just return the computed value... Thoughts?

I should update the spec to better reflect implementations on this regard, btw...

Start with the supplied HTML test case and the getComputedStyle(tr) call, then read the linked Bugzilla and jQuery reports alongside the current CSSOM/spec wording. Compare the reported Gecko, Blink/WebKit, and EdgeHTML behavior for table-row width and height; done means the expected behavior and corresponding spec text are agreed and documented.