Refactor "semantic_and" emitter function a bit

src/emitter.js

@@ -724,9 +724,9 @@ PEG.compiler.emitter = function(ast) {
 
     semantic_and: function(node, context) {
       return formatCode(
-        '#{resultVar} = (function() {#{actionCode}})() ? "" : null;',
+        '#{resultVar} = (function() {#{node.code}})() ? "" : null;',
         {
-          actionCode: node.code,
+          node:      node,
           resultVar: resultVar(context.resultIndex)
         }
       );