Remove unnecessary %UnwrapGlobalProxy calls from object-observe.js

src/object-observe.js

Index: src/object-observe.js
diff --git a/src/object-observe.js b/src/object-observe.js
index e822f0bd497588715e70c3300737b9e72a8e9134..c4ddd181d2841c479c3de34bd6d683554e2352bd 100644
--- a/src/object-observe.js
+++ b/src/object-observe.js
@@ -80,13 +80,9 @@ function GetWeakMapWrapper() {
 
   MapWrapper.prototype = {
     get: function(key) {
-      key = %UnwrapGlobalProxy(key);
-      if (!IS_SPEC_OBJECT(key)) return UNDEFINED;
       return %WeakCollectionGet(this.map_, key);
     },
     set: function(key, value) {
-      key = %UnwrapGlobalProxy(key);
-      if (!IS_SPEC_OBJECT(key)) return UNDEFINED;
       %WeakCollectionSet(this.map_, key, value);
     },
     has: function(key) {