Javascript XMLSerializer serializeToString() inconsistent

Not sure which browser is correct but I found a problem while trying to Parse XML (as a string) in javascript. IE10 removes the declaration tags whereas Firefox returns everything.

This was crucial in rendering word documents (saved as xml). The second declaration line helps windows determine the xml file should be opened by Word. My goal was to do a simple Word merge using only client side javascript.

<?xml version="1.0" encoding="UTF-8" standalone="yes"?>
<?mso-application progid="Word.Document"?>
<pkg:package xmlns:pkg="">
  <pkg:part pkg:name="/_rels/.rels" pkg:contentType="application/vnd.openxmlformats-package.relationships+xml" pkg:padding="512">
      <Relationships xmlns=""><Relationship Id="rId3" Type="" Target="docProps/app.xml"/><Relationship Id="rId2" Type="" Target="docProps/core.xml"/><Relationship Id="rId1" Type="" Target="word/document.xml"/></Relationships>