chore: clean up scroll-state solution

* Clean up scroll-state solution code for merge.

Author: puckowski

packages/less/src/less/tree/nested-at-rule.js

@@ -5,12 +5,6 @@ import Anonymous from './anonymous';
 import Expression from './expression';
 import * as utils from '../utils';
 
-const NESTABLE_UNMERGED_KEYWORD_SET = new Set([
-    'and',
-    'not',
-    'or'
-]);
-
 const NestableAtRulePrototype = {
 
     isRulesetLike() {
@@ -37,10 +31,6 @@ const NestableAtRulePrototype = {
         for (let index = 0; index < exprValues.length; ++index) {
             expr = exprValues[index];
 
-            if (NESTABLE_UNMERGED_KEYWORD_SET.has(expr.value)) {
-                continue;
-            }
-
             if (expr.type === 'Keyword' && index + 1 < exprValues.length) {
                 paren =  exprValues[index + 1];