ASSERT on loading qml file

Loading the attached QML file leads to the following ASSERT

ASSERT: "e->declarativeType->attachedPropertiesId() != -1" in file qml/v4/qdeclarativev4compiler.cpp, line 313

This is believed to be due to the "property Item item: Item" line, which no longer asserts if it ends with "Item {}".

It probably isn't valid QML, but this should lead to a compile error pointing to the offended line instead of an unhelpful assert.