Popup: blue focus flash on android 4.2

So I tested this with Browserstack on android 4.2 and it fixed the problem.  However, when I run "grunt test" there are a number of test cases failing.  @arschmitz suggested I do a pull request so he can take a look.  So don't merge if it's breaking tests! :)
In b14dd31f64c914e46e4460d61bd0cbb3232cf103, @TrueEddie found that you must also not call ```.blur()``` if that which you would blur is the body, for the same IE reason that you must not call ```.blur()``` on the window. So, you must add a second condition here:
```JS
&& this.document[ 0 ].activeElement.nodeName.toLowerCase() !== "body"
```

In fact, we should probably write a new widget-level method, ```_safelyBlur()```, and call it from both here and ```_handleDocumentFocusIn()```. From here, we would call it like this: ```this._safelyBlur( this.document[ 0 ].activeElement )``` ...