gistfile1.js

if( window.frames.length > 0 )
  console.log( "First frame:", window.frames[0] );

gistfile2.txt

First frame: undefined

gistfile3.js

var activeElement = document.activeElement;

if( activeElement === document.body){
  for( var i = 0; i < window.frames.length; ++i ){
    activeElement = frames[i].document.activeElement;
    if( activeElement !== frames[i].document.body ) break;
  }
}
/* Act on element */

gistfile4.js

chrome.tabs.executeScript( null, {
  allFrames : true,
  file: "file.js"
});

gistfile5.js

var activeElement = document.activeElement;
if( window.frames.length > 0 && window.frames[0] !== undefined )
  console.log( "Bug 20773 is fixed! Please alert http://www.github.com/Celc" );
if( activeElement !== document.body ){
  /* Act on element */
}