Manipulation: Tolerate XMLNode host object input to getAll

Fixes [#15151](http://bugs.jquery.com/ticket/15151)
Ref 25712d7

```
   raw     gz Sizes                                                            
246903  73144 dist/jquery.js                                                   
 84490  29523 dist/jquery.min.js                                               

   raw     gz Compared to master @ 39b76064d9400295a383291ab6e821e259b67832    
  +150    +45 dist/jquery.js                                                   
   +18     +5 dist/jquery.min.js
```
-2 to jquery.min.js.gz, but I'm not sure it's worth it. All we need is yet another failure when IE$Future helpfully adds the method.