Make redo command not to set invalid selection

third_party/WebKit/LayoutTests/editing/undo/redo-selection-modify-crash.html

+<script src="../../resources/testharness.js"></script>
+<script src="../../resources/testharnessreport.js"></script>
+<script src="../assert_selection.js"></script>
+<div id="log"></div>
+<script>
+test(() => {
+    assert_selection(
+        '<div contenteditable>|foo<br><i>bar</i></div>',
+        selection => {
+            // Make base/extent and start/end different.
+            selection.modify('extend', 'forward', 'word');
+            selection.document.execCommand('justifyLeft');
+            selection.document.execCommand('undo');
+            // Remove an anchor node for extent position of redo
+            selection.document.querySelector('i').remove();
+            selection.document.execCommand('redo');
+        },
+        navigator.platform.indexOf('Mac') == 0
+            ? '<div contenteditable>^foo|<br></div>'
+            : '<div contenteditable>^foo<br>|</div>');
+});
+</script>