Per section 7.1.5 Named Browsing Contexts of the WHATWG HTML specification:
> A valid browsing context name or keyword is any string that is either a valid browsing context name or that is an ASCII case-insensitive match for one of: _blank, _self, _parent, or _top.
However, the behavior observed is that case-mixed variants of `_blank` are treated as non-keyword browsing context names. To reproduce, e.g.:
1. `window.open` into `_bLAnk`
2. `window.open` into `_bLAnk`
Browser should create two new browsing contexts, treating `_bLAnk` as a case-insensitive match for the keyword `_blank`.
Browser only creates one new browsing context. The second invocation of `window.open` reuses the `_bLAnk` browsing context created by the first invocation.
Relevant web-platform-tests: https://github.com/w3c/web-platform-tests/pull/5145
Filed an HTML issue, so this might not be a bug -
Concluded in https://github.com/whatwg/html/issues/2443#issuecomment-289043039 that case-insensitive is better.
Created attachment 306240 [details]
*** Bug 169748 has been marked as a duplicate of this bug. ***
*** Bug 170128 has been marked as a duplicate of this bug. ***
Comment on attachment 306240 [details]
Clearing flags on attachment: 306240
Committed r214944: <http://trac.webkit.org/changeset/214944>
All reviewed patches have been landed. Closing bug.