chore: add slash to appAssets in karma.conf (angular#329) (angular#351)

Add leading slash to appAssets variable
closes angular#329

Author: wardbell

karma.conf.js

@@ -1,8 +1,8 @@
 module.exports = function(config) {
 
-  var appBase    = 'app/';      // transpiled app JS and map files
-  var appSrcBase = 'app/';      // app source TS files
-  var appAssets  = 'base/app/'; // component assets fetched by Angular's compiler
+  var appBase    = 'app/';       // transpiled app JS and map files
+  var appSrcBase = 'app/';       // app source TS files
+  var appAssets  = '/base/app/'; // component assets fetched by Angular's compiler
 
   // Testing helpers (optional) are conventionally in a folder called `testing`
   var testingBase    = 'testing/'; // transpiled test JS and map files