extension that adds some useful methods to any ScalaJS object

I added several (I hope) useful methods for any ScalaJS object to dom extensions:
1) def \(key:String):Option[js.Dynamic] that allows to get properties as Options There is also an extension to Option[js.Dynamic] that allows to do more complicated things like val value:Option[js.Dynamic] =  fooBar \ "child" \ "grandchild" \ "grandgrandchild"
2) def ===(other:Any):Boolean that allows to take into consideration possible Undefined values when comparing to null