Revert of [proxies] Implement [[Enumerate]] and [[OwnPropertyKeys]]

src/js/proxy.js

Index: src/js/proxy.js
diff --git a/src/js/proxy.js b/src/js/proxy.js
index d1202f7066bd2d66170f7518f0b95376fb77807a..3885e408add350acff7d74276a48a28f7eb8cb5c 100644
--- a/src/js/proxy.js
+++ b/src/js/proxy.js
@@ -152,30 +152,31 @@
   return enumerableNames
 }
 
-// Implements part of ES6 9.5.11 Proxy.[[Enumerate]]:
-// Call the trap, which should return an iterator, exhaust the iterator,
-// and return an array containing the values.
-function ProxyEnumerate(trap, handler, target) {
-  // 7. Let trapResult be ? Call(trap, handler, «target»).
-  var trap_result = %_Call(trap, handler, target);
-  // 8. If Type(trapResult) is not Object, throw a TypeError exception.
-  if (!IS_SPEC_OBJECT(trap_result)) {
-    throw MakeTypeError(kProxyHandlerReturned, handler, "non-Object",
-                        "enumerate");
-  }
-  // 9. Return trapResult.
-  var result = [];
-  for (var it = trap_result.next(); !it.done; it = trap_result.next()) {
-    var key = it.value;
-    // Not yet spec'ed as of 2015-11-25, but will be spec'ed soon:
-    // If the iterator returns a non-string value, throw a TypeError.
-    if (!IS_STRING(key)) {
-      throw MakeTypeError(kProxyHandlerReturned, handler, "non-String",
-                          "enumerate-iterator");
-    }
-    result.push(key);
-  }
-  return result;
+function DerivedEnumerateTrap() {
+  var names = this.getPropertyNames()
+  var enumerableNames = []
+  for (var i = 0, count = 0; i < names.length; ++i) {
+    var name = names[i]
+    if (IS_SYMBOL(name)) continue
+    var desc = this.getPropertyDescriptor(TO_STRING(name))
+    if (!IS_UNDEFINED(desc)) {
+      if (!desc.configurable) {
+        throw MakeTypeError(kProxyPropNotConfigurable,
+                            this, name, "getPropertyDescriptor")
+      }
+      if (desc.enumerable) enumerableNames[count++] = names[i]
+    }
+  }
+  return enumerableNames
+}
+
+function ProxyEnumerate(proxy) {
+  var handler = %GetHandler(proxy)
+  if (IS_UNDEFINED(handler.enumerate)) {
+    return %Apply(DerivedEnumerateTrap, handler, [], 0, 0)
+  } else {
+    return ToNameArray(handler.enumerate(), "enumerate", false)
+  }
 }
 
 //-------------------------------------------------------------------