onAttributeChange
Listen for attribute change mutations on any node within the documentElement.
    onAttributeChange( documentElement, callback )
  
  
  
  Parameters
- documentElement 
{Node}:The documentElement on which to listen for removal mutations.
 - callback 
{function}:The callback called when an attribute change mutation is dispatched.
 
Returns
 {function}: 
The callback to remove the mutation listener.