title: How to get Document or Compilation from SyntaxNode or SyntaxTree?
body: <p>I'm writing a <code>SyntaxRewriter</code>, so I have a <code>SyntaxNode</code> coming into my visit method (actually a <code>IdentifierNameSyntax</code>).</p>
  
  <p>What I need to do is work out what symbol the identifier presents, which I can do using a <code>SemanticModel</code>.</p>
  
  <p>As I understand it I can get a <code>SemanticModel</code> from either a <code>Document</code> or a <code>Compilation</code>.</p>
  
  <p>So, ideally I want to navigate to the <code>Document</code> or <code>Compilation</code> from the syntax  node.</p>
  
  <p>Is this possible?</p>