[proxies] Make Object.prototype.isPrototypeOf work with proxies.

src/objects.cc

Index: src/objects.cc
diff --git a/src/objects.cc b/src/objects.cc
index 5bf38b462484ff077c0860f47082afc5fea5534d..6bebf59545e4e573f4960b83ffc8924bf4497e29 100644
--- a/src/objects.cc
+++ b/src/objects.cc
@@ -1283,12 +1283,13 @@ void JSObject::SetNormalizedProperty(Handle<JSObject> object,
 }
 
 
-bool Object::HasInPrototypeChain(Isolate* isolate, Object* target) {
-  PrototypeIterator iter(isolate, this, PrototypeIterator::START_AT_RECEIVER);
+Maybe<bool> Object::HasInPrototypeChain(Isolate* isolate, Handle<Object> object,
+                                        Handle<Object> proto) {
+  PrototypeIterator iter(isolate, object, PrototypeIterator::START_AT_RECEIVER);
   while (true) {
-    iter.AdvanceIgnoringProxies();
-    if (iter.IsAtEnd()) return false;
-    if (iter.IsAtEnd(target)) return true;
+    if (!iter.AdvanceFollowingProxies()) return Nothing<bool>();
+    if (iter.IsAtEnd()) return Just(false);
+    if (iter.IsAtEnd(proto)) return Just(true);
   }
 }