[css-color-4][editorial] Use the correct attribute to hide tests.

Author: tabatkins

css-color-4/Overview.bs

@@ -4738,7 +4738,7 @@ Acknowledgments</h2>
 
 Thanks for the feedback from Emilio Cobos Álvarez, Marc Attinasi, Chris Bai, Amelia Bellamy-Royds, Lars Borg, Mike Bremford, Bert Bos, Andreu Botella, Dan Burzo, Joe Clark, Max Derhak, fantasai, Simon Fraser, Patrick Garies, Tony Graham, Ian Hickson, Phil Green, Dean Jackson, Andreas Kraushaar, Pierre-Anthony Lemieux, Susan Lesch, Alex LeDonne, Cameron McCormack, Krzysztof Maczy&#x0144;ski, Chris Moschini, Chris Murphy, Jonathan Neal, Chris Needham, Christoph P&auml;per, Steven Pemberton, David Perrell, Brad Pettit, Jacob Refstrup, Craig Revie, Melanie Richards, Florian Rivoal, Joseph Salowey, Simon Sapin, Dave Singer, Igor Snitkin, Jonathan Stanley, Andrew Thompson, Lea Verou, Mark Watson, Russ Weakley, Natalie Weizenbaum, Etan Wexler, David Woolley, Boris Zbarsky, Steve Zilles, the XSL FO subgroup of the XSL working group, the <a href="https://www.w3.org/community/colorweb/">Color on the Web community group</a> and all the rest of the <a href="http://lists.w3.org/Archives/Public/www-style/">www-style</a> community.
 
-<wpt ignore title="CSS Color 3 tests, not relevant for this level">
+<wpt hidden title="CSS Color 3 tests, not relevant for this level">
 background-color-hsl-001.html
 background-color-hsl-002.html
 background-color-hsl-003.html