Remove unnecessary coupling between Promise tests and Object.observe

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

Index: test/mjsunit/es6/debug-promises/throw-caught-all.js
diff --git a/test/mjsunit/es6/debug-promises/throw-caught-all.js b/test/mjsunit/es6/debug-promises/throw-caught-all.js
index 2fbf05141d56d018f3115a8a5e82b8cfcd709b43..bd6d343f827f8d3dc11f7ec1f136999d895c8b3a 100644
--- a/test/mjsunit/es6/debug-promises/throw-caught-all.js
+++ b/test/mjsunit/es6/debug-promises/throw-caught-all.js
@@ -62,10 +62,7 @@ function testDone(iteration) {
     }
   }
 
-  // Run testDone through the Object.observe processing loop.
-  var dummy = {};
-  Object.observe(dummy, checkResult);
-  dummy.dummy = dummy;
+  %EnqueueMicrotask(checkResult);
 }
 
 testDone(0);