[CSS Grid Layout] Support "sparse" in auto-placed items locked to a row/column

LayoutTests/fast/css-grid-layout/resources/grid.css

 .grid {
     display: grid;
     background-color: grey;
 }
 
 .indefiniteSizeGrid {
     display: grid;
     background-color: grey;
     width: -webkit-min-content;
     height: auto;
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     grid-column: 2 / 3;
     grid-row: 2 / 3;
 }
 
 .endSecondRowEndSecondColumn {
     background-color: orange;
     grid-column-end: 3;
     grid-row-end: 3;
 }
 
+.thirdRowSecondColumn {
+    background-color: red;
+    grid-column: 2;
+    grid-row: 3;
+}
+
 .firstAutoRowSecondAutoColumn {
     grid-row: 1 / auto;
     grid-column: 2 / auto;
 }
 
 .autoLastRowAutoLastColumn {
     grid-row: auto / -1;
     grid-column: auto / -1;
 }
 
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     grid-column: span 3;
     grid-row: span 2;
 }
 
 .autoRowSpanning3AutoColumnSpanning2 {
     background-color: indigo;
     grid-column: span 2;
     grid-row: span 3;
 }
 
+.autoRowFirstColumnSpanning2 {
+    background-color: maroon;
+    grid-column: 1 / span 2;
+    grid-row: auto;
+}
+
+.autoRowSecondColumnSpanning2 {
+    background-color: olive;
+    grid-column: 2 / span 2;
+    grid-row: auto;
+}
+
+.firstRowSpanning2AutoColumn {
+    background-color: maroon;
+    grid-column: auto;
+    grid-row: 1 / span 2;
+    height: 100%;
+}
+
+.secondRowSpanning2AutoColumn {
+    background-color: olive;
+    grid-column: auto;
+    grid-row: 2 / span 2;
+    height: 100%;
+}
+
 /* Grid element flow. */
 .gridAutoFlowColumnSparse {
     grid-auto-flow: column;
 }
 
 .gridAutoFlowColumnDense {
     grid-auto-flow: column dense;
 }
 
 .gridAutoFlowRowSparse {
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     -webkit-writing-mode: horizontal-bt;
 }
 
 .directionRTL {
     direction: rtl;
 }
 
 .directionLTR {
     direction: ltr;
 }