[css-sizing-4] Add changes section.

Author: fantasai

css-sizing-4/Overview.bs

@@ -798,6 +798,61 @@ Percentage Sizing</h3>
 <h2 class=no-num id="changes">
 Changes</h2>
 
+<h3 class=no-num id="changes-2020-05">
+Recent Changes</h3>
+  Significant changes since the <a href="https://www.w3.org/TR/2020/WD-css-sizing-4-20200526/">26 May 2020 First Public Working Draft</a> include:
+
+	* Define [=ratio-determining axis=] as a term.
+
+	* Define that min/max sizing constraints are transferred across an aspect-ratio,
+		(<a href="https://github.com/w3c/csswg-drafts/issues/5257">Issue 5257</a>)
+		<blockquote>
+			<p>Additionally, sizing constraints in either axis
+			(the <var>origin</var> axis)
+			are transferred through the [=preferred aspect ratio=]
+			to the other axis (the <var>destination</var> axis)
+			as follows:
+
+			* First, any [=definite=] [=minimum size=] is converted and transferred
+				from the <var>origin</var> to <var>destination</var> axis.
+				This transferred minimum is capped
+				by any [=definite=] [=preferred size|preferred=] or [=maximum size=]
+				in the <var>destination</var> axis.
+			* Then, any [=definite=] [=maximum size=] is converted and transferred
+				from the <var>origin</var> to <var>destination</var>.
+				This transferred maximum is floored
+				by any [=definite=] [=preferred size|preferred=] or [=minimum size=]
+				in the <var>destination</var> axis
+				as well as by the transferred minimum, if any.
+
+			Note: The basic principle is that sizing constraints
+			transfer through the aspect-ratio to the other side
+			to preserve the aspect ratio to the extent that they can
+			without violating any sizes specified explictly on that affected axis.
+			<!-- This is the principle that drove the contents of the table in CSS2 Section 10.4. -->
+		</blockquote>
+
+	* Clarify that 'aspect-ratio' on a replaced element with only one intrinsic dimension determines the other dimension.
+		(<a href="https://github.com/w3c/csswg-drafts/issues/5306">Issue 5306</a>)
+		<blockquote>
+			<p>If a replaced element's only [=intrinsic dimension=]
+			is an intrinsic width or an intrinsic height,
+			giving it a [=preferred aspect ratio=]
+			also gives it an intrinsic height or width,
+			whichever was missing,
+			by transferring the existing size
+			through the [=preferred aspect ratio=].
+		</blockquote>
+
+	* Define that 'aspect-ratio' inhibits margin self-collapsing
+		(<a href="https://github.com/w3c/csswg-drafts/issues/5328">Issue 5328</a>)
+		<blockquote>
+			<p>For the purpose of margin collapsing ([[css2/box#collapsing-margins]]),
+			if the [=block axis=] is the [=ratio-dependent axis=],
+			it is not considered to have a [=computed value|computed=] 'block-size' of ''height/auto''.
+		</blockquote>
+
+
 <h3 class=no-num id="additions-L3">
 Additions Since Level 3</h3>