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chromium/third_party/blink/web_tests/editing/pasteboard/paste-text-013.html 

<!DOCTYPE html>
<script src="../../resources/testharness.js"></script>
<script src="../../resources/testharnessreport.js"></script>
See this bug: <a href="rdar://problem/3918712">&lt;rdar://problem/3918712&gt;</a> "Paste as Quotation" in Mail just pastes (&lt;blockquote&gt; tag seems to be lost).
Should see one box with blockquoted "foo" text, followed by another box with an "x" (not in a blockquote) and "foo" (in a blockquote).

<div id="sample" contenteditable><div><blockquote>foo</blockquote></div></div>
<div id="log"></div>
<script>
test(function() {
    var selection = window.getSelection();
    var sample = document.getElementById('sample');

    selection.collapse(sample, 0);
    for (i = 0; i < 4; i++)
        selection.modify('extend', 'forward', 'character');
    document.execCommand('copy');
    selection.modify('move', 'forward', 'character');
    document.execCommand('insertText', false, 'x');
    document.execCommand('paste');

    assert_equals(sample.innerHTML, '<div><blockquote>fooxfoo</blockquote></div>');
    assert_true(selection.isCollapsed);
    assert_equals(selection.anchorNode, sample.querySelector('blockquote').firstChild);
    assert_equals(selection.anchorOffset, 7);
});
</script>