Selection API: Do not change focus by Selection functions.

third_party/WebKit/LayoutTests/editing/editing.js

 //-------------------------------------------------------------------------------------------------------
 // Java script library to run editing layout tests
 
 var commandCount = 1;
 var commandDelay = window.location.search.substring(1);
 if (commandDelay == '')
     commandDelay = 0;
 var selection = window.getSelection();
 
 //-------------------------------------------------------------------------------------------------------
@@ skipping 909 matching lines @@
                     offset++;
                 return { 'node': node, 'offset': offset };
             }
 
             if (node.nodeName == 'BR' || node.nodeName == 'IMG')
                 return { 'node': node.parentNode, 'offset': offset };
 
             return null;
         });
 
+        for (var focusTarget = elem; focusTarget; focusTarget = focusTarget.parentNode) {
+            focusTarget.focus();

[yoichio, 2017/02/24 01:54:51]

Why do we need to focus on all ancestors?

[tkent, 2017/02/24 01:59:44]

This just focus on the nearest focusable ancestor.

+            if (focusTarget.ownerDocument.activeElement == focusTarget)
+                break;
+        }
         if (firstVisiblePosition)
             selection.collapse(firstVisiblePosition.node, firstVisiblePosition.offset);
         else
             selection.collapse(elem, 0);
     } else {
         selection.removeAllRanges();
     }
 }
 
 function runEditingTest() {
@@ skipping 81 matching lines @@
 function executeCommand(command,arg1,arg2) {
     if (commandDelay > 0) {
         queueCommand(runCommand, commandCount * commandDelay);
         commandCount++;
     }
     else {
         runCommand(command,arg1,arg2);
     }
 }