Move some code from Runtime_SetPrototype to JSObject::SetPrototype.

This is in preparation of implementing Reflect.setPrototypeOf.

R=verwaest@chromium.org
BUG=

Review URL: https://codereview.chromium.org/1409003005

Cr-Commit-Position: refs/heads/master@{#31432}

src/objects.cc

@@ -13881,11 +13881,55 @@ Handle<Map> Map::TransitionToPrototype(Handle<Map> map,
 MaybeHandle<Object> JSObject::SetPrototype(Handle<JSObject> object,
                                            Handle<Object> value,
                                            bool from_javascript) {
+  Isolate* isolate = object->GetIsolate();
+
+  const bool observed = from_javascript && object->map()->is_observed();
+  Handle<Object> old_value;
+  if (observed) {
+    old_value = Object::GetPrototypeSkipHiddenPrototypes(isolate, object);
+  }
+
+  Handle<Object> result;
+  ASSIGN_RETURN_ON_EXCEPTION(
+      isolate, result, SetPrototypeUnobserved(object, value, from_javascript),
+      Object);
+
+  if (observed) {
+    Handle<Object> new_value =
+        Object::GetPrototypeSkipHiddenPrototypes(isolate, object);
+    if (!new_value->SameValue(*old_value)) {
+      RETURN_ON_EXCEPTION(isolate,
+                          JSObject::EnqueueChangeRecord(
+                              object, "setPrototype",
+                              isolate->factory()->proto_string(), old_value),
+                          Object);
+    }
+  }
+
+  return result;
+}
+
+
+MaybeHandle<Object> JSObject::SetPrototypeUnobserved(Handle<JSObject> object,
+                                                     Handle<Object> value,
+                                                     bool from_javascript) {
 #ifdef DEBUG
   int size = object->Size();
 #endif
 
   Isolate* isolate = object->GetIsolate();
+
+  if (from_javascript) {
+    if (object->IsAccessCheckNeeded() &&
+        !isolate->MayAccess(handle(isolate->context()), object)) {
+      isolate->ReportFailedAccessCheck(object);
+      RETURN_EXCEPTION_IF_SCHEDULED_EXCEPTION(isolate, Object);
+      return isolate->factory()->undefined_value();
+    }
+  } else {
+    DCHECK(!object->IsAccessCheckNeeded());
+  }
+
   // Strong objects may not have their prototype set via __proto__ or
   // setPrototypeOf.
   if (from_javascript && object->map()->is_strong()) {

src/objects.h

@@ -2521,6 +2521,9 @@ class JSObject: public JSReceiver {
   MUST_USE_RESULT static Maybe<bool> PreventExtensionsWithTransition(
       Handle<JSObject> object, ShouldThrow should_throw);
 
+  MUST_USE_RESULT static MaybeHandle<Object> SetPrototypeUnobserved(
+      Handle<JSObject> object, Handle<Object> value, bool from_javascript);
+
   DISALLOW_IMPLICIT_CONSTRUCTORS(JSObject);
 };
 

src/runtime/runtime-object.cc

@@ -181,8 +181,6 @@ RUNTIME_FUNCTION(Runtime_InternalSetPrototype) {
   DCHECK(args.length() == 2);
   CONVERT_ARG_HANDLE_CHECKED(JSObject, obj, 0);
   CONVERT_ARG_HANDLE_CHECKED(Object, prototype, 1);
-  DCHECK(!obj->IsAccessCheckNeeded());
-  DCHECK(!obj->map()->is_observed());
   Handle<Object> result;
   ASSIGN_RETURN_FAILURE_ON_EXCEPTION(
       isolate, result, JSObject::SetPrototype(obj, prototype, false));
@@ -195,29 +193,6 @@ RUNTIME_FUNCTION(Runtime_SetPrototype) {
   DCHECK(args.length() == 2);
   CONVERT_ARG_HANDLE_CHECKED(JSObject, obj, 0);
   CONVERT_ARG_HANDLE_CHECKED(Object, prototype, 1);
-  if (obj->IsAccessCheckNeeded() &&
-      !isolate->MayAccess(handle(isolate->context()), obj)) {
-    isolate->ReportFailedAccessCheck(obj);
-    RETURN_FAILURE_IF_SCHEDULED_EXCEPTION(isolate);
-    return isolate->heap()->undefined_value();
-  }
-  if (obj->map()->is_observed()) {
-    Handle<Object> old_value =
-        Object::GetPrototypeSkipHiddenPrototypes(isolate, obj);
-    Handle<Object> result;
-    ASSIGN_RETURN_FAILURE_ON_EXCEPTION(
-        isolate, result, JSObject::SetPrototype(obj, prototype, true));
-
-    Handle<Object> new_value =
-        Object::GetPrototypeSkipHiddenPrototypes(isolate, obj);
-    if (!new_value->SameValue(*old_value)) {
-      RETURN_FAILURE_ON_EXCEPTION(
-          isolate, JSObject::EnqueueChangeRecord(
-                       obj, "setPrototype", isolate->factory()->proto_string(),
-                       old_value));
-    }
-    return *result;
-  }
   Handle<Object> result;
   ASSIGN_RETURN_FAILURE_ON_EXCEPTION(
       isolate, result, JSObject::SetPrototype(obj, prototype, true));