[CSS Grid Layout] Fix positioned grid children position and size

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;
 }
 
 .inline-grid {
     display: inline-grid;
     background-color: grey;
 }
 
 .firstRowFirstColumn {
     background-color: blue;
     grid-column: 1;
     grid-row: 1;
 }
 
+.onlyFirstRowOnlyFirstColumn {
+    background-color: blue;
+    grid-column: 1 / 2;
+    grid-row: 1 / 2;
+}
+
 .firstRowSecondColumn {
     background-color: lime;
     grid-column: 2;
     grid-row: 1;
 }
 
+.onlyFirstRowOnlySecondColumn {
+    background-color: lime;
+    grid-column: 2 / 3;
+    grid-row: 1 / 2;
+}
+
 .secondRowFirstColumn {
     background-color: purple;
     grid-column: 1;
     grid-row: 2;
 }
 
+.onlySecondRowOnlyFirstColumn {
+    background-color: purple;
+    grid-column: 1 / 2;
+    grid-row: 2 / 3;
+}
+
 .secondRowSecondColumn {
     background-color: orange;
     grid-column: 2;
     grid-row: 2;
 }
 
+.onlySecondRowOnlySecondColumn {
+    background-color: orange;
+    grid-column: 2 / 3;
+    grid-row: 2 / 3;
+}
+
+.endSecondRowEndSecondColumn {
+    background-color: orange;
+    grid-column-end: 3;
+    grid-row-end: 3;
+}
+
 .firstAutoRowSecondAutoColumn {
     grid-row: 1 / auto;
     grid-column: 2 / auto;
 }
 
 .autoLastRowAutoLastColumn {
     grid-row: auto / -1;
     grid-column: auto / -1;
 }
 
@@ skipping 141 matching lines @@
     -webkit-writing-mode: vertical-lr;
 }
 
 .horizontalBT {
     -webkit-writing-mode: horizontal-bt;
 }
 
 .directionRTL {
     direction: rtl;
 }