Ignore hide events that aren't from nodes

[drnic]

I was using dropdown on an input controller watching for focus events:

    <input type="text" name="search" id="search"
      placeholder="Search..."
      data-action="focus->dropdown#toggle blur->dropdown#toggle focus@window->dropdown#hide">

Without this fix, I was getting the following error when the blur event on the document triggered hide:

Error invoking action "focus@window->dropdown#hide"

TypeError: Failed to execute 'contains' on 'Node': parameter 1 is not of type 'Node'.
    at extended.hide (dropdown_controller.js:134:22)
    at Binding.invokeWithEvent (stimulus.js:281:25)
    at Binding.handleEvent (stimulus.js:253:18)
    at EventListener.handleEvent (stimulus.js:31:25)