Added to Element:
      querySelector
Added to Node:
      appendChild
      replaceChild
      hasAttributes
      hasChildNodes
      contains
      normalize
      lastChild
      parentNode
      previousSibling
Added to CharacterData:
      appendData

Fixed bug in removeChild, removed child now returned
Fixed bug in insertBefore, newElement was not being checked as a node properly
Fixed bug with firstChild and lastChild, undefined was returned instead of null