pull out the input processing out of the parser class and a few small improvements - the no js option now applies to all js, including that within quotes. The Javascript node now also returns the right index.

lib/less/tree/js-eval-node.js

@@ -10,6 +10,11 @@ jsEvalNode.prototype.evaluateJavaScript = function (expression, env) {
         that = this,
         context = {};
 
+    if (env.javascriptEnabled !== undefined && !env.javascriptEnabled) {
+        throw { message: "You are using JavaScript, which has been disabled." ,
+            index: this.index };
+    }
+
     expression = expression.replace(/@\{([\w-]+)\}/g, function (_, name) {
         return that.jsify(new(Variable)('@' + name, that.index).eval(env));
     });