Can you explain this better? How does it break?

If I change the test to just

expect(annotate(({ fn(x) { return; } }).fn)).toEqual(['x']);

then the JS parser complains about the syntax. It claims there is a missing : after fn and stops

Which JS parser? What browser versions are you talking about? Are you talking about the test file failing to parse in older browsers? Or what?

Without the eval trick, Safari 8.0.7 (10600.7.12) [This is the latest Safari version]
throws this error when parsing the file to run the tests

SyntaxError: Unexpected token '('. Expected a ':' following the property name 'fn'.

After throwing this error, no tests are executed.

Alright, I'd rather we jUst put the test in a different source file which is only loaded in known supported browsers, because I really don't want to rely on eval. Take your pick and document clearly the approach you've taken. Otherwise LGTM

This regex will also match MS Edge's navigator (but it's OK, since it understands the syntax as well).
(But the comment is misleading :P)

I do not have access to MS Edge and it is currently not supported by saurcelabs, so this will have to make it.

On a side note, I find it somehow strange for MS Edge user agent to have the word "Chrome" in it

I know.
BTW, it also has Safari and (of course) Edge (for interoperability reasons - or so I've read :P).