Actually that's not true at least in Firefox and probably chrome.

Take a look at http://jsfiddle.net/2LsSg/.

  window.onload/g@http://fiddle.jshell.net/2LsSg/show/:23:5  
  window.onload/f@http://fiddle.jshell.net/2LsSg/show/:26:5  
  @http://fiddle.jshell.net/2LsSg/show/ line 29 > eval:1:1  
  window.onload@http://fiddle.jshell.net/2LsSg/show/:29:1

(I guess jsfiddle wraps the JS code in a window.onload handler, which makes this a bit more ugly)