[css-grid] Remove grid-auto-position and grid-auto-flow:none, add grid-auto-flow:stack, per WG resolution.

Author: tabatkins

css-grid/Overview.bs

@@ -1447,8 +1447,8 @@ Automatic Placement: the 'grid-auto-flow' property</h3>
 
 	<pre class='propdef'>
 	Name: grid-auto-flow
-	Value: none | [ [ row | column ] && dense? ]
-	Initial: none
+	Value: [ [ row | column ] && dense? ] | [ stack && [ row | column ]? ]
+	Initial: row
 	Applies to: <a>grid containers</a>
 	Inherited: no
 	Percentages: n/a
@@ -1461,11 +1461,6 @@ Automatic Placement: the 'grid-auto-flow' property</h3>
 	and whether rows or columns are added as needed to accommodate the content.
 
 	<dl dfn-for=grid-auto-flow dfn-type=value>
-		<dt><dfn>none</dfn>
-		<dd>
-			Rather than use the auto-placement algorithm,
-			auto-placed <a>grid items</a> are simply positioned according to the 'grid-auto-position' property.
-
 		<dt><dfn>row</dfn>
 		<dd>
 			The <a>auto-placement algorithm</a> places items
@@ -1486,18 +1481,26 @@ Automatic Placement: the 'grid-auto-flow' property</h3>
 			permanently skipping spaces that it can't fill with the current <a>grid item</a>.)
 
 			Note: This may cause items to appear out-of-order.
+
+		<dt><dfn>stack</dfn>
+		<dd>
+			The auto-placement algorithm is run with a single hypothetical 1×1 grid item,
+			as if ''grid-auto-flow: row'' or ''grid-auto-flow: column'' were specified,
+			depending on whether ''row'' or ''column'' is specified alongside it,
+			respectively.
+			If neither ''row'' nor ''column'' are specified,
+			it defaults to running the algorithm as if ''grid-auto-flow: row'' were specified.
+
+			Wherever the hypothetical item would be placed,
+			all auto-placed items are placed there,
+			stacked atop one another.
+			(This happens even if the auto-placed item is greater than 1×1,
+			even if doing so would cause it to overlap explicitly-placed <a>grid items</a>.)
 	</dl>
 
 	Note: A future level of this module is expected to add a value that flows auto-positioned items together into a single “default” cell.
 
-	<p class='issue'>
-		Win8 compat might require the ''grid-auto-flow/none'' value to stay the initial value,
-		but it's not a very good value,
-		because by default the entire contents of a grid container will end up stacked on top of each other.
-		See <a href="http://lists.w3.org/Archives/Public/www-archive/2013Aug/0024.html">proposals to address this</a>
-		while addressing use cases and back-compat.
-
-		Auto-placement takes <a>grid items</a> in <a>order-modified document order</a>.
+	Auto-placement takes <a>grid items</a> in <a>order-modified document order</a>.
 
 	<div class='example'>
 		In the following example, there are three columns, each auto-sized to their contents.
@@ -1716,36 +1719,6 @@ Automatic Grid Item Placement Algorithm</h4>
 			reset the <a>auto-placement cursor</a> to 1/1 each time an item is placed.
 	</ol>
 
-<h3 id="grid-auto-position-property">
-Default Position: the 'grid-auto-position' property</h3>
-
-	<pre class='propdef'>
-	Name: grid-auto-position
-	Value: <<grid-line>> / <<grid-line>>
-	Initial: 1 / 1
-	Applies to: <a>grid containers</a>
-	Inherited: no
-	Percentages: n/a
-	Media: visual
-	Computed value: specified value
-	</pre>
-
-	If a <a>grid container</a> doesn't specify an automatic-placement strategy through 'grid-auto-flow',
-	any grid items with an <a>automatic grid position</a> are instead all placed at the default position
-	specified by 'grid-auto-position'.
-
-	Interpret the two <<grid-line>>s as if they were specified in 'grid-column-start' and 'grid-row-start', respectively,
-	of a hypothetical <a>grid item</a>,
-	treating <a value for=grid-row-start>auto</a> as ''1'' for this purpose.
-	The resulting lines of the <a>grid container</a>
-	become a <a>definite grid position</a> in both axes
-	for the auto-placed <a>grid items</a>.
-
-	<p class="issue">
-		These properties might not be necessary in this level,
-		if we can provide a more reasonable default behavior
-		by, e.g., searching for an empty slot to stack items into
-		instead of always using 1,1 by default.
 
 <h2 id='grid-shorthand'>
 Grid Definition Shorthand: the 'grid' property</h2>