AXSelection: Strengthened table test

I tried hard, but I wasn't able to make non-text positions work inside a table.
The DOM parser collects all the non-white space text nodes between the table cells and places them in a single text node before the table element.
This is not part of the accessibility code, but is how the DOM parser works.
The alternative, which I implemented in this patch, is to enhance the table test by adding more selections inside text nodes.
<table>
  ^<tr>
    <td>column</td>
  </tr>|
</table>
Becomes in the DOM tree:
Body
++#Text "\n^|\n"
++Table
++++Tr
++++++Td

R=dmazzoni@chromium.org

Change-Id: I99c4a1f14805f9a0ba4addbaaff9bad1b1a0b86b
Reviewed-on: https://chromium-review.googlesource.com/c/1332728Reviewed-by: Dominic Mazzoni <dmazzoni@chromium.org>
Commit-Queue: Nektarios Paisios <nektar@chromium.org>
Cr-Commit-Position: refs/heads/master@{#607505}

third_party/blink/renderer/modules/accessibility/testing/data/selection/table-ax.txt

 
 ================================================================================
-AXSelection from AX object anchored position in "WebArea": "", 0 to AX object anchored position in "WebArea": "", 0
+AXSelection from AX text position in "StaticText": "Sum", 0 to AX text position in "StaticText": "Subtraction", 11
 ================================================================================
-|++<Table>
+++<Table>
 ++++<Row>
 ++++++<ColumnHeader: Sum>
-++++++++<StaticText: Sum>
+^++++++++<StaticText: ^Sum>
 ++++++<ColumnHeader: Subtraction>
-++++++++<StaticText: Subtraction>
+++++++++<StaticText: Subtraction|>
 ++++<Row>
 ++++++<Cell: 10>
 ++++++++<StaticText: 10>
@@ -25,9 +25,9 @@ AXSelection from AX object anchored position in "WebArea": "", 0 to AX object an
 ++++++++<StaticText: 3>
 
 ================================================================================
-AXSelection from AX object anchored position in "WebArea": "", 0 to AX object anchored position in "WebArea": "", 0
+AXSelection from AX text position in "StaticText": "7", 1 to AX text position in "StaticText": "10", 0
 ================================================================================
-|++<Table>
+++<Table>
 ++++<Row>
 ++++++<ColumnHeader: Sum>
 ++++++++<StaticText: Sum>
@@ -35,9 +35,9 @@ AXSelection from AX object anchored position in "WebArea": "", 0 to AX object an
 ++++++++<StaticText: Subtraction>
 ++++<Row>
 ++++++<Cell: 10>
-++++++++<StaticText: 10>
+|++++++++<StaticText: |10>
 ++++++<Cell: 7>
-++++++++<StaticText: 7>
+++++++++<StaticText: 7^>
 ++++<Row>
 ++++++<Cell: 2>
 ++++++++<StaticText: 2>
@@ -50,9 +50,9 @@ AXSelection from AX object anchored position in "WebArea": "", 0 to AX object an
 ++++++++<StaticText: 3>
 
 ================================================================================
-AXSelection from AX object anchored position in "WebArea": "", 0 to AX object anchored position in "WebArea": "", 0
+AXSelection from AX text position in "StaticText": "2", 1 to AX text position in "StaticText": "4", 0
 ================================================================================
-|++<Table>
+++<Table>
 ++++<Row>
 ++++++<ColumnHeader: Sum>
 ++++++++<StaticText: Sum>
@@ -65,9 +65,9 @@ AXSelection from AX object anchored position in "WebArea": "", 0 to AX object an
 ++++++++<StaticText: 7>
 ++++<Row>
 ++++++<Cell: 2>
-++++++++<StaticText: 2>
+++++++++<StaticText: 2^>
 ++++++<Cell: 4>
-++++++++<StaticText: 4>
+|++++++++<StaticText: |4>
 ++++<Row>
 ++++++<Cell: 12>
 ++++++++<StaticText: 12>
@@ -75,14 +75,14 @@ AXSelection from AX object anchored position in "WebArea": "", 0 to AX object an
 ++++++++<StaticText: 3>
 
 ================================================================================
-AXSelection from AX text position in "StaticText": "Sum", 0 to AX text position in "StaticText": "Subtraction", 11
+AXSelection from AX text position in "StaticText": "12", 0 to AX text position in "StaticText": "3", 1
 ================================================================================
 ++<Table>
 ++++<Row>
 ++++++<ColumnHeader: Sum>
-^++++++++<StaticText: ^Sum>
+++++++++<StaticText: Sum>
 ++++++<ColumnHeader: Subtraction>
-++++++++<StaticText: Subtraction|>
+++++++++<StaticText: Subtraction>
 ++++<Row>
 ++++++<Cell: 10>
 ++++++++<StaticText: 10>
@@ -95,6 +95,6 @@ AXSelection from AX text position in "StaticText": "Sum", 0 to AX text position
 ++++++++<StaticText: 4>
 ++++<Row>
 ++++++<Cell: 12>
-++++++++<StaticText: 12>
+^++++++++<StaticText: ^12>
 ++++++<Cell: 3>
-++++++++<StaticText: 3>
+++++++++<StaticText: 3|>

third_party/blink/renderer/modules/accessibility/testing/data/selection/table.html

@@ -9,20 +9,20 @@
         </tr>
       </thead>
       <tfoot>
-        ^<tr>
-          <td>12</td>
-          <td>3</td>
-        </tr>|
+        <tr>
+          <td>^12</td>
+          <td>3|</td>
+        </tr>
       </tfoot>
       <tbody>
         <tr>
-          ^<td>10</td>
-          <td>7</td>|
+          <td>|10</td>
+          <td>7^</td>
+        </tr>
+        <tr>
+          <td>2^</td>
+          <td>|4</td>
         </tr>
-        ^<tr>
-          <td>2</td>
-          <td>4</td>
-        </tr>|
       </tbody>
     </table>
   </body>