[ESnext] Implement Object spread

src/runtime/runtime-object.cc

 // Copyright 2014 the V8 project authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #include "src/runtime/runtime-utils.h"
 
 #include "src/arguments.h"
 #include "src/bootstrapper.h"
 #include "src/debug/debug.h"
 #include "src/isolate-inl.h"
@@ skipping 732 matching lines @@
     JSFunction::SetName(getter, name, isolate->factory()->get_string());
   }
 
   RETURN_FAILURE_ON_EXCEPTION(
       isolate,
       JSObject::DefineAccessor(object, name, getter,
                                isolate->factory()->null_value(), attrs));
   return isolate->heap()->undefined_value();
 }
 
+RUNTIME_FUNCTION(Runtime_CopyDataProperties) {
+  HandleScope scope(isolate);
+  DCHECK(args.length() == 2);
+  CONVERT_ARG_HANDLE_CHECKED(JSReceiver, target, 0);
+  CONVERT_ARG_HANDLE_CHECKED(Object, source, 1);
+
+  // 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();
+  }
+
+  MAYBE_RETURN(

[adamk, 2016/12/29 18:32:46]

Can this fail?

[gsathya, 2017/01/05 22:18:36]

Yes, the error needs to propagate up from SetOrCopyDataProperties

+      JSReceiver::SetOrCopyDataProperties(isolate, target, source, false),
+      isolate->heap()->exception());
+
+  return isolate->heap()->undefined_value();
+}
 
 RUNTIME_FUNCTION(Runtime_DefineSetterPropertyUnchecked) {
   HandleScope scope(isolate);
   DCHECK(args.length() == 4);
   CONVERT_ARG_HANDLE_CHECKED(JSObject, object, 0);
   CONVERT_ARG_HANDLE_CHECKED(Name, name, 1);
   CONVERT_ARG_HANDLE_CHECKED(JSFunction, setter, 2);
   CONVERT_PROPERTY_ATTRIBUTES_CHECKED(attrs, 3);
 
   if (String::cast(setter->shared()->name())->length() == 0) {
@@ skipping 168 matching lines @@
   if (!success) return isolate->heap()->exception();
   MAYBE_RETURN(
       JSReceiver::CreateDataProperty(&it, value, Object::THROW_ON_ERROR),
       isolate->heap()->exception());
   return *value;
 }
 
 
 }  // namespace internal
 }  // namespace v8