fix(issue:4264) strip line comment from expression (#4293)

* Fix for issue #4264. Strip line comments from expressions to avoid
  invalid CSS output.

Author: puckowski

packages/less/src/less/parser/parser.js

@@ -2418,7 +2418,7 @@ const Parser = function Parser(context, imports, fileInfo, currentIndex) {
 
                 do {
                     e = this.comment();
-                    if (e) {
+                    if (e && !e.isLineComment) {
                         entities.push(e);
                         continue;
                     }

packages/test-data/css/_main/variables.css

@@ -80,3 +80,18 @@
 .radio_checked {
   border-color: #fff;
 }
+div#apple {
+  color: blue;
+}
+div#banana {
+  color: blue;
+}
+div#cherry {
+  color: blue;
+}
+div#carrot {
+  color: blue;
+}
+div#potato {
+  color: blue;
+}

packages/test-data/less/_main/variables.less

@@ -143,3 +143,19 @@
 .@{radio-cls-checked} {
   border-color: #fff;
 }
+
+@items:
+// Fruit
+    apple,
+    banana,
+    cherry,
+// Vegetables
+    carrot,
+    potato,
+;
+
+each(@items, {
+  div#@{value} {
+    color: blue;
+  }
+})