[css-values-3] Update Changes list

Author: fantasai

css-values-3/Overview.bs

@@ -2129,10 +2129,16 @@ Changes</h2>
 			This effectively removes that syntax from 'object-position',
 			but allows <<position>> to be re-used e.g. in [[CSS-TRANSFORMS-1]] for 3D positions.
 			(See <a href="https://lists.w3.org/Archives/Public/www-style/2017Feb/0052.html">discussion</a>.)
+		<li>Reverted previous change to allow zero angles to drop their unit; this will instead be special-cased where needed for backwards-compatibility.
+			(See <a href="https://lists.w3.org/Archives/Public/www-style/2017Apr/0027.html">discussion</a>)
 		<li>Fixed grammar error that disallowed numeric expressions as denominators in ''calc()''.
 			(<a href="https://drafts.csswg.org/css-values-3/issues-cr-2016#issue-12">Issue 12</a>)
 		<li>Defined handling of font-relative units outside the context of an element.
 			(<a href="https://drafts.csswg.org/css-values-3/issues-cr-2016#issue-9">Issue 9</a>)
+		<li>Defined that ''0'' parses as <<number>> if it's ambiguous whether it's a <<number>> or a <<length>>.
+			(<a href="https://github.com/w3c/csswg-drafts/issues/489">Issue 489</a>)
+		<li>Removed (unused) ability for percentages to be treated as a <<number>> type in ''calc()''.
+			(<a href="https://github.com/w3c/csswg-drafts/issues/1463">Issue 1463</a>)
 		<li>Clarified that high-resolution screens should anchor on device pixels, not physical units.
 			(<a href="https://drafts.csswg.org/css-values-3/issues-cr-2016#issue-8">Issue 8</a>)
 		<li>Clarified definition of ''url()'' to normatively say that it accepts unquoted syntax.