Use more human-readable descriptions in object-fit.

Refer to cover/constraint sizing in common algos section.

Author: fantasai

css3-images/Overview.html

@@ -2007,36 +2007,36 @@ <h3 id=object-fit><span class=secno>5.5. </span> Sizing Objects: the
 
   <p>The &lsquo;<a href="#object-fit0"><code
    class=property>object-fit</code></a>&rsquo; property specifies how the
-   contents of a replaced element should be scaled relative to the box
-   established by its used height and width. Not all replaced elements can be
-   scaled, but images typically can.
+   contents of a replaced element should be fitted to the box established by
+   its used height and width.
 
   <dl>
    <dt>&lsquo;<code class=css>fill</code>&rsquo;
 
-   <dd>The object's <a href="#concrete-object-size"><i>concrete object
-    size</i></a> is the element's used width and height.
+   <dd>The replaced content is sized to fill the element's content box: the
+    object's <a href="#concrete-object-size"><i>concrete object size</i></a>
+    is the element's used width and height.
 
    <dt>&lsquo;<code class=css>contain</code>&rsquo;
 
-   <dd>The object's <a href="#concrete-object-size"><i>concrete object
-    size</i></a> is the largest rectangle that has the object's <a
-    href="#intrinsic-aspect-ratio"><i>intrinsic aspect ratio</i></a>, and
-    additionally has neither width nor height larger than the replaced
-    element's used width and height, respectively.
+   <dd>The replaced content is sized to maintain its aspect ratio while
+    fitting within the element's content box: its <a
+    href="#concrete-object-size"><i>concrete object size</i></a> is resolved
+    as a <a href="#contain-constraint"><i>contain constraint</i></a> against
+    the element's used width and height.
 
    <dt>&lsquo;<code class=css>cover</code>&rsquo;
 
-   <dd>The object's <a href="#concrete-object-size"><i>concrete object
-    size</i></a> the smallest rectangle that has the object's <a
-    href="#intrinsic-aspect-ratio"><i>intrinsic aspect ratio</i></a>, and
-    additionally has neither width nor height smaller than the replaced
-    element's used width and height, respectively.
+   <dd>The replaced content is sized to maintain its aspect ratio while
+    filling the element's entire content box: its <a
+    href="#concrete-object-size"><i>concrete object size</i></a> is resolved
+    as a <a href="#cover-constraint"><i>cover constraint</i></a> against the
+    element's used width and height.
 
    <dt>&lsquo;<code class=css>none</code>&rsquo;
 
-   <dd>Don't resize the replaced content to fit the element's used width and
-    height: determine the object's <a
+   <dd>The replaced content is not resized to fit inside the element's
+    content box: determine the object's <a
     href="#concrete-object-size"><i>concrete object size</i></a> using the <a
     href="#default-sizing-algorithm"><i>default sizing algorithm</i></a> with
     no specified size, and a <a href="#default-object-size"><i>default object
@@ -2055,12 +2055,6 @@ <h3 id=object-fit><span class=secno>5.5. </span> Sizing Objects: the
      intrinsic aspect ratio, so the concept of "smaller" is well-defined.</p>
   </dl>
 
-  <p>If the replaced element's content does not have an <a
-   href="#intrinsic-aspect-ratio"><i>intrinsic aspect ratio</i></a>, the
-   &lsquo;<code class=css>cover</code>&rsquo; and &lsquo;<code
-   class=css>contain</code>&rsquo; values are treated as &lsquo;<code
-   class=css>fill</code>&rsquo;.
-
   <p>If the content does not completely fill the replaced element's content
    box, the unfilled space shows the replaced element's background. Since
    replaced elements always clip their contents to the content box, the

css3-images/Overview.src.html

@@ -1250,28 +1250,29 @@ <h3 id="object-fit">
 	</table>
 
 	<p>The 'object-fit' property specifies how the contents of a replaced element
-	should be scaled relative to the box established by its used height and width.
-	Not all replaced elements can be scaled, but images typically can.</p>
+	should be fitted to the box established by its used height and width.</p>
 
 	<dl>
 		<dt>''fill''</dt>
-		<dd>The object's <i>concrete object size</i> is the element's used width and height.</dd>
+		<dd>The replaced content is sized to fill the element's content box: the
+		object's <i>concrete object size</i> is the element's used width and
+		height.</dd>
 
 		<dt>''contain''</dt>
-		<dd>The object's <i>concrete object size</i> is the largest rectangle that
-		has the object's <i>intrinsic aspect ratio</i>, and additionally has neither
-		width nor height larger than the replaced element's used width and height,
-		respectively.</dd>
+		<dd>The replaced content is sized to maintain its aspect ratio while fitting
+		within the element's content box: its <i>concrete object size</i> is
+		resolved as a <i>contain constraint</i> against the element's used width
+		and height.</dd>
 
 		<dt>''cover''</dt>
-		<dd>The object's <i>concrete object size</i> the smallest rectangle that
-		has the object's <i>intrinsic aspect ratio</i>, and additionally has neither
-		width nor height smaller than the replaced element's used width and height,
-		respectively.</dd>
+		<dd>The replaced content is sized to maintain its aspect ratio while filling
+		the element's entire content box: its <i>concrete object size</i> is
+		resolved as a <i>cover constraint</i> against the element's used width
+		and height.</dd>
 
 		<dt>''none''</dt>
-		<dd>Don't resize the replaced content to fit the element's used width and
-		height: determine the object's <i>concrete object size</i> using the
+		<dd>The replaced content is not resized to fit inside the element's content
+		box: determine the object's <i>concrete object size</i> using the
 		<i>default sizing algorithm</i> with no specified size, and a
 		<i>default object size</i> equal to the replaced element's used width and
 		height.</dd>
@@ -1286,9 +1287,6 @@ <h3 id="object-fit">
 		</dd>
 	</dl>
 
-	<p>If the replaced element's content does not have an <i>intrinsic aspect
-	ratio</i>, the ''cover'' and ''contain'' values are treated as ''fill''.</p>
-
 	<p>If the content does not completely fill the replaced element's content box,
 	the unfilled space shows the replaced element's background.
 	Since replaced elements always clip their contents to the content box, the