Fixed errors occurring because of undefined properties on nested paths.

lib/handlebars/compiler/compiler.js

@@ -532,7 +532,7 @@ Handlebars.JavaScriptCompiler = function() {};
 
     lookup: function(name) {
       var topStack = this.topStack();
-      this.source.push(topStack + " = " + this.nameLookup(topStack, name, 'context') + ";");
+      this.source.push(topStack + " = " + topStack + " ? " + this.nameLookup(topStack, name, 'context') + " : " + topStack + ";");
     },
 
     pushStringParam: function(string) {

spec/qunit_spec.js

@@ -964,7 +964,6 @@ module("Regressions")
 test("GH-94: Cannot read property of undefined", function() {
 	var data = {"books":[{"title":"The origin of species","author":{"name":"Charles Darwin"}},{"title":"Lazarillo de Tormes"}]};
 	var string = "{{#books}}{{title}}{{author.name}}{{/books}}";
-	p(tpl);
 	shouldCompileTo(string, data, "The origin of speciesCharles DarwinLazarillo de Tormes",
                   "Renders without an undefined property error");
 });