Make Object.observe on the global object functional

src/object-observe.js

Index: src/object-observe.js
diff --git a/src/object-observe.js b/src/object-observe.js
index c9ae652a53e1d273871bbdb510ce5d31bd89fa3d..8c2895f4bdeaf7f14076feae20f4c6b790f96868 100644
--- a/src/object-observe.js
+++ b/src/object-observe.js
@@ -49,7 +49,7 @@ InternalObjectHashTable.prototype = {
         %ObjectHashTableSet(observationState[this.tableName], key, value);
   },
   has: function(key) {
-    return %ObjectHashTableHas(observationState[this.tableName], key);
+    return !IS_UNDEFINED(this.get(key));
   }
 };