CONSOLE MESSAGE: line 10: MessageEvent received in main world
CONSOLE MESSAGE: line 11: detail was {"foo":5,"bar":"hello","targetWorld":"main"}
CONSOLE MESSAGE: line 3: MessageEvent received in isolated world
CONSOLE MESSAGE: line 4: detail was {"foo":5,"bar":"hello","targetWorld":"isolated"}
Tests that properties of MessageEvents initialized with initMessageEvent() are cloned when accessed in isolated worlds.