anchor.diff:      e.style.color = "#333";
       e.style.font = "400 14px 'Montserrat', sans-serif";
   
  -    var r = row();
  -    r.append(cell("Container"));
  -    r.append(cell("Count"));
  -    r.append(cell("Target"));
  -    e.append(r);
  -
  -    for (var entry in callSite.entries) {
  +    if (callSite.entries.isEmpty) {
  +      e.append(row('Did not execute'));
  +    } else {
         var r = row();
  -      r.append(cell(serviceRef(entry.receiverContainer)));
  -      r.append(cell(entry.count.toString()));
  -      r.append(cell(serviceRef(entry.target)));
  +      r.append(cell("Container"));
  +      r.append(cell("Count"));
  +      r.append(cell("Target"));
         e.append(r);
  +
  +      for (var entry in callSite.entries) {
  +        var r = row();
  +        r.append(cell(serviceRef(entry.receiverContainer)));
  +        r.append(cell(entry.count.toString()));
  +        r.append(cell(serviceRef(entry.target)));
  +        e.append(r);
  +      }
       }
   
       return e;
  
positive.code: class CallSiteAnnotation extends Annotation {
    CallSite callSite;
  
    Element row() {
      var e = new DivElement();
      e.style.display = "table-row";
      return e;
    }
  
  
negative.code:   infoBox.style.border = 'solid black 2px';
    infoBox.style.zIndex = '10';
    infoBox.style.backgroundColor = 'white';
    infoBox.style.cursor = 'auto';
    infoBox.style.display = 'none';  // Initially hidden.
  
    var show = false;
    content.onClick.listen((event) {
      show = !show;
      infoBox.style.display = show ? 'block' : 'none';
      content.style.backgroundColor = show ? 'white' : '';
    });
  
    // Causes infoBox to be positioned relative to the bottom-left of content.
    content.style.display = 'inline-block';
    content.style.cursor = 'pointer';
    content.append(infoBox);
  }
  
  