[css-grid] Allow percentage-based tracks to back-compute the percentage per WG resolution. This is optional for now; still under discussion in WG (globally across CSS).

Author: fantasai

css-grid/Overview.bs

@@ -1346,9 +1346,14 @@ Explicit Track Sizing: the 'grid-template-rows' and 'grid-template-columns' prop
 			A non-negative percentage, as defined by CSS3 Values. [[!CSS3VAL]]
 			<<percentage>> values are relative to the <a>inline size</a> of the <a>grid container</a> in column <a>grid tracks</a>,
 			and the <a>block size</a> of the <a>grid container</a> in row <a>grid tracks</a>.
-			If the <a lt="inline size">inline</a> or <a>block size</a> of the <a>grid container</a>
-			is <a>indefinite</a>,
-			<<percentage>> values relative to that size are treated as <a value for=width>auto</a>.
+			If the size of the <a>grid container</a>
+			depends on the size of its tracks,
+			then the <<percentage>>
+			must be treated as <a value for=width>auto</a>.
+			The UA <em>may</em> adjust the intrinsic size contributions of the track
+			to the size of the <a>grid container</a>
+			and increase the final size of the track
+			by the minimum amount that would result in honoring the percentage.
 
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 		<dd>

css-grid/issues-wd-20160519.bsi

@@ -212,6 +212,6 @@ Summary:   Back-compute percentage gaps
 From:      Mats Palmgren
 Comment:   https://github.com/w3c/csswg-drafts/issues/472
 Response:  https://github.com/w3c/csswg-drafts/issues/472#issuecomment-248655700
-Open:      Indeterminite (made undefined)
+Closed:    Indeterminite (made undefined)
 Resolved:  TPAC 2016
 ----

css-grid/issues-wd-20160519.html

@@ -239,13 +239,13 @@ <h1>CSS Grid Layout Level 1 Disposition of Comments for 2016-05-19 WD</h1>
 <span>Response:  <a href='https://github.com/w3c/csswg-drafts/issues/494#issuecomment-248465154'>https://github.com/w3c/csswg-drafts/issues/494#issuecomment-248465154</a></span>
 <span class="a">Closed:    Accepted</span>
 <span>Resolved:  Editorial</span></pre>
-<pre class='open ' id='issue-26'>
+<pre class=' ' id='issue-26'>
 <span>Issue 26. <a href='#issue-26'>#</a></span>
 <span>Summary:   Back-compute percentage gaps</span>
 <span>From:      Mats Palmgren</span>
 <span>Comment:   <a href='https://github.com/w3c/csswg-drafts/issues/472'>https://github.com/w3c/csswg-drafts/issues/472</a></span>
 <span>Response:  <a href='https://github.com/w3c/csswg-drafts/issues/472#issuecomment-248655700'>https://github.com/w3c/csswg-drafts/issues/472#issuecomment-248655700</a></span>
-<span class="">Open:      Indeterminite (made undefined)</span>
+<span class="">Closed:    Indeterminite (made undefined)</span>
 <span>Resolved:  TPAC 2016</span></pre>
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