Issue 6740: Display registered MutationObservers for an element

I am the 'testElement', my parent is 'content'

Steps to reproduce

  1. Open Firebug and enabled the Console panel
  2. Execute this expression in the Command Line:


    You should see list of event listeners and mutation observers handling events coming from the element (displaying as two tables). You can also click on the return value and inspect all details in the DOM panel.

  3. Click one of the buttons below to see logs from mutation observers in the Console panel.

There are following registered event listeners:
  1. 'click' => 'testElement'
  2. 'click' => 'testElement'
  3. 'mousemove' => 'testElement'
  4. 'mousemove' => 'content'
  5. 'mousedown' => document
  6. 'mouseup' => window
There are following registered mutation observers (subtree=true) for:
  1. 'testElement'
  2. 'testElement'
  3. 'content'
  4. document