localize urls in nested items

Author: sokra

index.js

@@ -154,6 +154,15 @@ function localizeDeclNode(node, context) {
         return newNode;
       }
       break;
+
+    case 'nested-item':
+      var newNodes = node.nodes.map(function(n) {
+        return localizeDeclValue(n, context);
+      });
+      node = Object.create(node);
+      node.nodes = newNodes;
+      break;
+
     case 'url':
       if(context.options && context.options.rewriteUrl) {
         newNode = Object.create(node);

test.js

@@ -363,6 +363,7 @@ var tests = [
     input: '.a { background: url(./image.png); }\n' +
       ':global .b { background: url(image.png); }\n' +
       '.c { background: url("./image.png"); }\n' +
+      '.d { background: -webkit-image-set(url("./image.png") 1x, url("./image2x.png") 2x); }\n' +
       '@font-face { src: url("./font.woff"); }\n' +
       '@-webkit-font-face { src: url("./font.woff"); }\n' +
       '@media screen { .a { src: url("./image.png"); } }\n' +
@@ -377,6 +378,7 @@ var tests = [
     expected: ':local(.a) { background: url((local\\)./image.png\\\"local\\\"); }\n' +
       '.b { background: url((global\\)image.png\\\"global\\\"); }\n' +
       ':local(.c) { background: url(\"(local)./image.png\\\"local\\\"\"); }\n' +
+      ':local(.d) { background: -webkit-image-set(url(\"(local)./image.png\\\"local\\\"\") 1x, url(\"(local)./image2x.png\\\"local\\\"\") 2x); }\n' +
       '@font-face { src: url(\"(local)./font.woff\\\"local\\\"\"); }\n' +
       '@-webkit-font-face { src: url(\"(local)./font.woff\\\"local\\\"\"); }\n' +
       '@media screen { :local(.a) { src: url("(local)./image.png\\"local\\""); } }\n' +