[css-color-4] Correct 'longer' hue adjust, for identical colors. Fix w3c#7147

Author: svgeesus

css-color-4/Overview.bs

@@ -5138,11 +5138,11 @@ Hue interpolation</h3>
 	Angles are adjusted so that |θ₂ - θ₁| ∈ {0, [180, 360)}. In pseudo-Javascript:
 		<pre>
 		if (0 < θ₂ - θ₁ < 180) {
-			θ₁ += 360;
-		}
-		else if (-180 < θ₂ - θ₁ < 0) {
 			θ₂ += 360;
 		}
+		else if (-180 < θ₂ - θ₁ <= 0) {
+			θ₁ += 360;
+		}
 		</pre>
 
 	<h4 id="hue-increasing"><dfn export>increasing</dfn></h4>