Element.insert does not allow inserting a text node

[jwestbrook]

previous lighthouse ticket #1125
by arno

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Hi,
Element.insert(node) does not work when node is a text node:

var el = new Element('a', { href: 'link'});
var text = document.createTextNode('content');
el.insert(text);

will fail with exception:
"insert is undefined" on line 2054 for 1.7_rc2

that's because

if (Object.isString(insertions) || Object.isNumber(insertions) ||
    Object.isElement(insertions) || (insertions && (insertions.toElement || insertions.toHTML)))