remove array comprehension if template as it's nastier than using ast-types

lib/6to5/templates/if.js

@@ -1,3 +0,0 @@
-if (STATEMENT) {
-
-}

lib/6to5/transformers/array-comprehension.js

@@ -1,4 +1,5 @@
 var util = require("../util");
+var b    = require("recast").types.builders;
 var _    = require("lodash");
 
 var single = function (node) {
@@ -45,14 +46,7 @@ var multiple = function (node, file) {
 
       // add a filter as this is our final stop
       if (node.filter) {
-        var filter = util.template("if", {
-          STATEMENT: node.filter
-        });
-
-        // set if body
-        filter.consequent.body = [child];
-
-        child = filter;
+        var child = b.ifStatement(node.filter, b.blockStatement([child]));
       }
     }