Remove support for Object.observe

test/mjsunit/migrations.js

Index: test/mjsunit/migrations.js
diff --git a/test/mjsunit/migrations.js b/test/mjsunit/migrations.js
index a18d884059baf40cc59294bbef5ed921b0bc20f0..2bd70fb771967253107c6863b5322111f2602035 100644
--- a/test/mjsunit/migrations.js
+++ b/test/mjsunit/migrations.js
@@ -2,7 +2,6 @@
 // Use of this source code is governed by a BSD-ayle license that can be
 // found in the LICENSE file.
 
-// Flags: --harmony-object-observe
 // Flags: --allow-natives-syntax --track-fields --expose-gc
 
 var global = Function('return this')();
@@ -275,10 +274,6 @@ var migrations = [
     },
   },
   {
-    name: "observe",
-    migr: function(o, i) { Object.observe(o, function(){}); },
-  },
-  {
     name: "seal",
     migr: function(o, i) { Object.seal(o); },
   },