only add generator tests if we have generators

Author: christkv

test/runner.js

@@ -253,9 +253,6 @@ var testFiles =[
   , '/test/functional/promises_cursor_tests.js'
   , '/test/functional/operation_promises_example_tests.js'
 
-  // Generator tests
-  , '/test/functional/operation_generators_example_tests.js'
-
   // Logging tests
   , '/test/functional/logger_tests.js'
 
@@ -288,6 +285,13 @@ var testFiles =[
   , '/test/functional/authentication_tests.js'
 ]
 
+// Check if we support es6 generators
+try {
+  eval("(function *(){})");
+  // Generator tests
+  testFiles.push('/test/functional/operation_generators_example_tests.js');
+} catch(err) {}
+
 // Add all the tests to run
 testFiles.forEach(function(t) {
   if(t != "") runner.add(t);