LibJS: Add property configuration transitions

Object.defineProperty() can now change the attributes of a property
already on the object. Internally this becomes a shape transition with
the TransitionType::Configure. Such transitions don't expand the
property storage capacity, but rather simply keep attributes up to date
when generating a property table.

1 files changed, 1 insertions, 1 deletions

diff --git a/Libraries/LibJS/Runtime/ObjectConstructor.cpp b/Libraries/LibJS/Runtime/ObjectConstructor.cpp
index 5d3b54fdfb..0ed34c26b5 100644
--- a/Libraries/LibJS/Runtime/ObjectConstructor.cpp
+++ b/Libraries/LibJS/Runtime/ObjectConstructor.cpp
@@ -127,7 +127,7 @@ Value ObjectConstructor::define_property(Interpreter& interpreter)
     auto& object = interpreter.argument(0).as_object();
     auto& descriptor = interpreter.argument(2).as_object();
 
-    Value value = descriptor.get("value").value_or(js_undefined());
+    Value value = descriptor.get("value").value_or(Value());
     u8 configurable = descriptor.get("configurable").value_or(Value(false)).to_boolean() * Attribute::Configurable;
     u8 enumerable = descriptor.get("enumerable").value_or(Value(false)).to_boolean() * Attribute::Enumerable;
     u8 writable = descriptor.get("writable").value_or(Value(false)).to_boolean() * Attribute::Writable;