[css-color-5] Adjustments to edge cases and set notation for hue interpolation types (w3c#5278)

Author: dbaron

css-color-5/Overview.bs

@@ -752,37 +752,37 @@ Unless the type of hue interpolation is ''specified'', both angles need to be co
 One way to do this is <code><i>θ</i> = ((<i>θ</i> % 360) + 360) % 360</code>.
 
 : ''shorter''
-:: Angles are adjusted so that θ₂ - θ₁ ∈ [0, 180). In pseudo-Javascript:
+:: Angles are adjusted so that θ₂ - θ₁ ∈ [-180, 180]. In pseudo-Javascript:
 	<pre>
-	if (θ₂ - θ₁ >= 180) {
+	if (θ₂ - θ₁ > 180) {
 		θ₁ += 360;
 	}
-	else if (θ₂ - θ₁ <= -180) {
+	else if (θ₂ - θ₁ < -180) {
 		θ₂ += 360;
 	}
 	</pre>
 
 : ''longer''
-:: Angles are adjusted so that θ₂ - θ₁ ∈ [180, 360). In pseudo-Javascript:
+:: Angles are adjusted so that |θ₂ - θ₁| ∈ {0, [180, 360)}. In pseudo-Javascript:
 	<pre>
 	if (0 < θ₂ - θ₁ < 180) {
-	  θ₁ += 360;
+		θ₁ += 360;
 	}
 	else if (-180 < θ₂ - θ₁ < 0) {
-	  θ₂ += 360;
+		θ₂ += 360;
 	}
 	</pre>
 
 : ''increasing''
-:: Angles are adjusted so that θ₂ - θ₁ ∈ [0, 360) and θ₁ ≤ θ₂. In pseudo-Javascript:
+:: Angles are adjusted so that θ₂ - θ₁ ∈ [0, 360). In pseudo-Javascript:
 	<pre>
 	if (θ₂ < θ₁) {
 		θ₂ += 360;
 	}
 	</pre>
 
 : ''decreasing''
-:: Angles are adjusted so that θ₂ - θ₁ ∈ [0, 360) and θ₁ ≥ θ₂. In pseudo-Javascript:
+:: Angles are adjusted so that θ₂ - θ₁ ∈ (-360, 0]. In pseudo-Javascript:
 	<pre>
 	if (θ₁ < θ₂) {
 		θ₁ += 360;