Fix eternal reload on pages with no stylesheets.

This fixes test-in-console, which was never completing test runs because
the page would reload constantly (or something).

packages/webapp/webapp_client.js

@@ -1,6 +1,9 @@
 WebApp = {
 
   _isCssLoaded: function () {
+    if (document.styleSheets.length === 0)
+      return true;
+
     return _.find(document.styleSheets, function (sheet) {
       if (sheet.cssText && !sheet.cssRules) // IE8
         return !sheet.cssText.match(/meteor-css-not-found-error/);