[proxies] Make Array.isArray respect proxies.

src/objects-inl.h

Index: src/objects-inl.h
diff --git a/src/objects-inl.h b/src/objects-inl.h
index 586e23d55921db8be5636c5a2a982ac57b9c8d8d..e524ed40247f9d584a3ff764e2cdca75e3874b0e 100644
--- a/src/objects-inl.h
+++ b/src/objects-inl.h
@@ -179,6 +179,23 @@ bool Object::IsUniqueName() const {
 }
 
 
+Maybe<bool> Object::IsArray() const {

[Benedikt Meurer, 2015/12/03 10:38:53]

Mhm, given that this can throw, we probably should handlify this guy. I.e. turn
it into static Maybe<bool> Object::IsArray(Handle<Object> arg).

[jochen (gone - plz use gerrit), 2015/12/03 10:40:53]

there needs to be a way to figure out whether something is an array without
throwing exceptions :-/

+  if (this->IsJSArray()) return Just(true);
+  if (this->IsJSProxy()) {
+    const JSProxy* proxy = JSProxy::cast(this);
+    if (proxy->IsRevoked()) {
+      Isolate* isolate = proxy->GetIsolate();
+      isolate->Throw(*isolate->factory()->NewTypeError(
+          MessageTemplate::kProxyRevoked,
+          isolate->factory()->NewStringFromAsciiChecked("IsArray")));
+      return Nothing<bool>();
+    }
+    return proxy->target()->IsArray();
+  }
+  return Just(false);
+}
+
+
 bool Object::IsCallable() const {
   return Object::IsHeapObject() && HeapObject::cast(this)->map()->is_callable();
 }