Remove unnecessary coupling between Promise tests and Object.observe

test/mjsunit/es6/debug-promises/reject-uncaught-uncaught.js

Index: test/mjsunit/es6/debug-promises/reject-uncaught-uncaught.js
diff --git a/test/mjsunit/es6/debug-promises/reject-uncaught-uncaught.js b/test/mjsunit/es6/debug-promises/reject-uncaught-uncaught.js
index 86e2a815e7257360e1995b50b6e39d9da8d583c4..ad19498b2855f92fde50df54e33d5242bee6d8e3 100644
--- a/test/mjsunit/es6/debug-promises/reject-uncaught-uncaught.js
+++ b/test/mjsunit/es6/debug-promises/reject-uncaught-uncaught.js
@@ -60,10 +60,7 @@ function testDone(iteration) {
     }
   }
 
-  // Run testDone through the Object.observe processing loop.
-  var dummy = {};
-  Object.observe(dummy, checkResult);
-  dummy.dummy = dummy;
+  Promise.resolve().then(checkResult);
 }
 
 testDone(0);