UserAgent: Mozilla/5.0 (Macintosh; Intel Mac OS X 10_11_6) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/56.0.2924.87 Safari/537.36

Steps to reproduce the problem:
1. `window.open` a document into `_tOP`

OR

2. `window.open` into `_seLF`

What is the expected behavior?
For `_tOP`: Browser should re-use the top-level browsing context, or current if it is also top

For `_seLF`: Browser should re-use current browsing context

What went wrong?
Browser opens document in new browsing context (treating `_tOP` and `_seLF` as new, named contexts instead of recognizing the keyword.

Did this work before? N/A 

Does this work in other browsers? Yes

Chrome version: 56.0.2924.87  Channel: n/a
OS Version: OS X 10.11.6
Flash Version: Shockwave Flash 25.0 r0

Related/see also:

https://bugs.chromium.org/p/chromium/issues/detail?id=702188 (_parent)
https://bugs.chromium.org/p/chromium/issues/detail?id=702178 (_blank)

Related WPT tests:
https://github.com/w3c/web-platform-tests/pull/5233