[ESnext] Implement Object Rest

src/runtime/runtime-object.cc

Index: src/runtime/runtime-object.cc
diff --git a/src/runtime/runtime-object.cc b/src/runtime/runtime-object.cc
index d1e57c00dd93577db40e91c9bcd8bc0ab086c896..0c3e1069db9edf41b5358528a71f964ba11ad21a 100644
--- a/src/runtime/runtime-object.cc
+++ b/src/runtime/runtime-object.cc
@@ -768,7 +768,7 @@ RUNTIME_FUNCTION(Runtime_DefineGetterPropertyUnchecked) {
 
 RUNTIME_FUNCTION(Runtime_CopyDataProperties) {
   HandleScope scope(isolate);
-  DCHECK(args.length() == 2);
+  DCHECK_EQ(2, args.length());
   CONVERT_ARG_HANDLE_CHECKED(JSObject, target, 0);
   CONVERT_ARG_HANDLE_CHECKED(Object, source, 1);
 
@@ -777,12 +777,32 @@ RUNTIME_FUNCTION(Runtime_CopyDataProperties) {
     return isolate->heap()->undefined_value();
   }
 
-  MAYBE_RETURN(
-      JSReceiver::SetOrCopyDataProperties(isolate, target, source, false),
-      isolate->heap()->exception());
+  MAYBE_RETURN(JSReceiver::SetOrCopyDataProperties(isolate, target, source,
+                                                   nullptr, false),
+               isolate->heap()->exception());
   return isolate->heap()->undefined_value();
 }
 
+RUNTIME_FUNCTION(Runtime_CopyDataPropertiesWithExcludedProperties) {
+  HandleScope scope(isolate);
+  DCHECK_LE(1, args.length());
+  CONVERT_ARG_HANDLE_CHECKED(Object, source, 0);
+
+  Arguments excluded_properties(1, args.arguments() - 1);

[adamk, 2017/01/12 22:43:08]

Passing 1 for length here seems wrong, how does this work for tests that pass in
multiple excluded properties?

Elsewhere I see this pattern of allocating a ScopedVector<Handle> and filling it
with the arguments. Perhaps we could do that here. It does call new, which is a
little strange, but it's still probably lower overhead than allocating a heap
object like a FixedArray. One advantage of going that route is it would be easy
to check that all the arguments are Names.

[gsathya, 2017/01/17 19:28:59]

Done.

+
+  // 2. If source is undefined or null, let keys be an empty List.
+  if (source->IsUndefined(isolate) || source->IsNull(isolate)) {
+    return isolate->heap()->undefined_value();
+  }
+
+  Handle<JSObject> target =
+      isolate->factory()->NewJSObject(isolate->object_function());
+  MAYBE_RETURN(JSReceiver::SetOrCopyDataProperties(isolate, target, source,
+                                                   &excluded_properties, false),
+               isolate->heap()->exception());
+  return *target;
+}
+
 RUNTIME_FUNCTION(Runtime_DefineSetterPropertyUnchecked) {
   HandleScope scope(isolate);
   DCHECK_EQ(4, args.length());