upgrade to angular 1.5.9

Change-Id: If3dda42818a2eb86f240f826bd67ba2f6e6741c4
diff --git a/karma.conf.js b/karma.conf.js
index 76d232c..3d07ec2 100644
--- a/karma.conf.js
+++ b/karma.conf.js
@@ -7,7 +7,7 @@
   /* eslint indent: [2,2], quotes: [2, "single"]*/
 
   // this is to load a different suite of test while developing
-  const testFiles = '*';
+  let testFiles = '*';
   if(process.argv[4]){
     testFiles = process.argv[4];
   }