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chromium/third_party/blink/web_tests/editing/selection/collapse/collapse_before_select.html 

<!doctype html>
<script src="../../../resources/testharness.js"></script>
<script src="../../../resources/testharnessreport.js"></script>
<div contenteditable id="anchor"><select><option>One</option></select>blaa</div>
<div id="log"></div>
<script>
test(function() {
    var selection = window.getSelection();
    var select = document.querySelector('select');
    selection.collapse(select, 0);

    var anchor = document.getElementById('anchor');
    assert_equals(selection.anchorNode, select, 'DOM anchorNode');
    assert_equals(selection.anchorOffset, 0, 'DOM anchorOffset');
    assert_equals(selection.focusNode, select, 'DOM focusNode');
    assert_equals(selection.focusOffset, 0, 'DOM focusOffset');

    assert_own_property(window, 'internals');
    assert_equals(internals.visibleSelectionAnchorNode, anchor, 'Canonicalized anchorNode');
    assert_equals(internals.visibleSelectionAnchorOffset, 0, 'Canonicalized anchorOffset');
    assert_equals(internals.visibleSelectionFocusNode, anchor, 'Canonicalized focusNode');
    assert_equals(internals.visibleSelectionFocusOffset, 0, 'Canonicalized focusOffset');
}, 'can not place canonicalized caret inside SELECT element');
</script>