add negative sign processing to CJK custom algorithms (w3c#12717)

Signed-off-by: saku <saku@email.sakupi01.com>

Author: sakupi01

css-counter-styles-3/Overview.bs

@@ -2200,6 +2200,9 @@ Chinese: ''simp-chinese-informal'', ''simp-chinese-formal'', ''trad-chinese-info
 		the representation is the character for 0 specified for the given counter style.
 		Skip the rest of this algorithm.
 
+		<li>If the counter value is negative,
+		instead use the absolute value of the counter value for the remaining steps of this algorithm.
+
 		<li>Initially represent the counter value as a decimal number.
 		For each digit that is not 0,
 		append the appropriate digit marker to the digit.
@@ -2214,7 +2217,12 @@ Chinese: ''simp-chinese-informal'', ''simp-chinese-formal'', ''trad-chinese-info
 
 		<li>Replace the digits 0-9 with the appropriate character
 		for the given counter style.
-		Return the resultant string as the representation of the counter value.
+
+		<li>If the counter value was negative,
+		prepend the appropriate negative sign character for the given counter style
+		as specified in the table of characters for each style.
+
+		<li>Return the resultant string as the representation of the counter value.
 	</ol>
 
 	For all of these counter styles,
@@ -2401,6 +2409,9 @@ Chinese: ''simp-chinese-informal'', ''simp-chinese-formal'', ''trad-chinese-info
 		the representation is the character for 0 specified for the given counter style.
 		Skip the rest of this algorithm.
 
+		<li>If the counter value is negative,
+		instead use the absolute value of the counter value for the remaining steps of this algorithm.
+
 		<li>Initially represent the counter value as a decimal number.
 		Starting from the right (ones place),
 		split the decimal number into groups of four digits.
@@ -2447,7 +2458,12 @@ Chinese: ''simp-chinese-informal'', ''simp-chinese-formal'', ''trad-chinese-info
 
 		<li>Replace the digits 0-9 with the appropriate character
 		for the given counter style.
-		Return the resultant string as the representation of the counter value.
+
+		<li>If the counter value was negative,
+		prepend the appropriate negative sign character for the given counter style
+		as specified in the table of characters for each style.
+
+		<li>Return the resultant string as the representation of the counter value.
 	</ol>
 
 	For all of these counter styles, the descriptors are the same as for the [[#limited-range-required|limited range variants]],