Now, you can optionally specify a ConsoleClient, to customise the
behaviour of the LibJS Console.
To customise the console, create a new ConsoleClient class that inherits
from JS::ConsoleClient and override all the abstract methods.
When Console::log() is called, if Console has a ConsoleClient,
ConsoleClient::log() is called instead.
These abstract methods are Value(void) functions: you can return a Value
which will be returned by the JavaScript function which calls that
method, in JavaScript.
e91ab0cb02