UserAgent: Mozilla/5.0 (X11; Ubuntu; Linux x86_64; rv:52.0) Gecko/20100101 Firefox/52.0

Example URL:
http://www.gtalbot.org/BrowserBugsSection/CSS3ConditionalRules/supports-caption-side-left.html

Steps to reproduce the problem:
Load self-explanatory test. Chrome (all versions) does *not* support 'caption-side: left'.

What is the expected behavior?
Since Chrome does not support 'caption-side: left', then Chrome, in that test page, should display "DOES NOT SUPPORT" in red.

What went wrong?
Chrome, in that test page, displays "SUPPORTS" in green. But again, this is not true: Chrome (all versions) does *not* support 'caption-side: left'.

Does it occur on multiple sites: N/A

Is it a problem with a plugin? No 

Did this work before? No 

Does this work in other browsers? Yes

Chrome version: 59.0.3067.0  Channel: dev
OS Version: 
Flash Version: irrelevant

Thread starts here:

http://lists.w3.org/Archives/Public/www-style/2017Apr/0021.html

2 people, besides me, believe that Chrome has a bug.

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"
The ‘@supports’ rule is a conditional group rule whose condition tests whether the user agent supports CSS property:value pairs. Authors can use it to write style sheets that use new features when available but degrade gracefully when those features are not supported. (...)
"
https://www.w3.org/TR/css3-conditional/#at-supports

Therefore, a supported property with an unsupported value must cause the @supports condition to fail.

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The test discloses the user agent string (thanks to a small inline script) so that I can use the test page for browsers in browser shot service sites.