This issue was originally filed by da...@altern.org

Try the sample code:

void main() {
  h.SpanElement span = new h.SpanElement();
  span.appendText('1\n2');
  for (h.Node testn in span.nodes) {
    print("${testn.nodeType} ${testn.$dom_localName} ${testn.nodeValue}");
  }
}

What is the expected output?
3 null 1
2

What do you see instead?
In Dartium or Firefox, I see the expected output. In IE9, I see:
3 null 1
1 br null
3 null 2

What version of the product are you using? On what operating system?
Dart SDK version 0.5.13.1_r23552
Windows 7 and IE9

Please provide any additional information below.
The API documentation for Element.appendText is "Adds the specified text as a text node after the last child of this element.". With IE9, dart2js is sometimes adding BR elements and text nodes instead of just using one text node as advertised...