[css-grid] Re-add the 'position all the non-auto-positioned elements' line to the placement algo.

Author: tabatkins

css-grid/Overview.bs

@@ -2526,7 +2526,9 @@ Grid Item Placement Algorithm</h3>
 	If it is instead set to ''grid-auto-flow/column'',
 	swap all mentions of rows and columns, inline and block, etc. in this algorithm.
 
-	1. <b>Process the items locked to a given row.</b>
+	1. <strong>Position anything that's not auto-positioned.</strong>
+
+	2. <strong>Process the items locked to a given row.</strong>
 
 		For each <a>grid item</a> with a <a>definite row position</a>
 		(that is, the 'grid-row-start' and 'grid-row-end' properties define a <a>definite grid position</a>),
@@ -2545,7 +2547,7 @@ Grid Item Placement Algorithm</h3>
 			to the earliest (smallest positive index) line index
 			that ensures this item’s <a>grid area</a> will not overlap any <a>occupied</a> grid cells.
 
-	2. <b>Determine the number of columns in the implicit grid.</b>
+	3. <strong>Determine the number of columns in the implicit grid.</strong>
 
 		Set the number of columns in the <a>implicit grid</a> to the larger of:
 
@@ -2577,7 +2579,7 @@ Grid Item Placement Algorithm</h3>
 			which is larger than the <a>explicit grid</a>’s 5 columns.
 		</div>
 
-	3. <b>Position the remaining grid items.</b>
+	4. <strong>Position the remaining grid items.</strong>
 
 		The <dfn export local-lt="cursor">auto-placement cursor</dfn> defines the current “insertion point” in the grid,
 		specified as a pair of row and column <a>grid lines</a>.