Remove unnecessary coupling between Promise tests and Object.observe

test/mjsunit/es6/debug-promises/reject-caught-all.js

Index: test/mjsunit/es6/debug-promises/reject-caught-all.js
diff --git a/test/mjsunit/es6/debug-promises/reject-caught-all.js b/test/mjsunit/es6/debug-promises/reject-caught-all.js
index 0fca57730a1430be493d7964cda0c1c18b93fb45..2cee8b9412a1199abaeb0edf06f7b5d1f048088c 100644
--- a/test/mjsunit/es6/debug-promises/reject-caught-all.js
+++ b/test/mjsunit/es6/debug-promises/reject-caught-all.js
@@ -63,10 +63,7 @@ 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);