Add support for @index in #each

lib/handlebars/base.js

@@ -56,13 +56,27 @@ Handlebars.registerHelper('blockHelperMissing', function(context, options) {
   }
 });
 
+Handlebars.K = function() {};
+
+Handlebars.createFrame = Object.create || function(object) {
+  Handlebars.K.prototype = object;
+  var obj = new Handlebars.K();
+  Handlebars.K.prototype = null;
+  return obj;
+};
+
 Handlebars.registerHelper('each', function(context, options) {
   var fn = options.fn, inverse = options.inverse;
-  var ret = "";
+  var ret = "", data;
+
+  if (options.data) {
+    data = Handlebars.createFrame(options.data);
+  }
 
   if(context && context.length > 0) {
     for(var i=0, j=context.length; i<j; i++) {
-      ret = ret + fn(context[i]);
+      if (data) { data.index = i; }
+      ret = ret + fn(context[i], { data: data });
     }
   } else {
     ret = inverse(this);