Log in the console all globals, still will not tell you where you created the global..

gistfile1.txt

/* Dump all 'user space' globals 
Many thanks to glutamat: http://stackoverflow.com/questions/14585537 */
void( (function()
{
  var w = document.body.appendChild( document.createElement("iframe") ).contentWindow,
  known = 
  [ 
    "screenLeft" , "screenTop" , "scrollX" , "scrollY" , "pageYOffset" , "pageXOffset" , /* Scrolling related built-ins */
    "innerWidth" , "innerHeight" , "outerWidth" , "outerHeight" , /* Size related built-ins */
    "defaultstatus" , "defaultStatus", /* Status bar text related built-ins */
    "frameElement" , "length" , /* Frame related built-ins */
    "opener" , "event" , "status" , "name" , "closed" , "external" , /* Generic Misc. */
    "devicePixelRatio" , /* Webkit & Opera Misc.*/
    "offscreenBuffering" ,  /* Webkit & IE Misc. */
    "chrome" , "Intl" , "v8Intl" /* Webkit */
  ],
  list = [], i = 1;
  for(var key in window)  
    if( window.hasOwnProperty(key) && w[key] === undefined  && !~known.indexOf(key) )       
      list.push(key);
  list.sort().forEach( function(s){ console.log( i++ , s )  } );
})());

You can use this as a this as a bookmarklet, this is definitely beta quality, do not use for nuclear reactors ;)