title: XSLT document('') function doesn't work
body: <p>As I understand from docs, XSLT function document() with empty string as parameter should read current XSLT document. But the following code doesn't work: </p>
  
  <pre><code>  &lt;xsl:stylesheet version="1.0" xmlns:xsl="http://www.w3.org/1999/XSL/Transform"&gt;
    &lt;state&gt;test2&lt;/state&gt;
     &lt;xsl:template match="/"&gt;
        test1
        &lt;xsl:value-of select="document('')/*/state"/&gt;
      &lt;/xsl:template&gt;
     &lt;/xsl:stylesheet&gt;
  </code></pre>
  
  <p>When I apply this XSLT to some XML (just  for example), I have only "test1" as output. Why line</p>
  
  <pre><code> &lt;xsl:value-of select="document('')/*/state"/&gt;
  </code></pre>
  
  <p>doesn't print "test2"? </p>