Initializing a new URL/NSURL instance is a chore especially when one
takes into account that the JavaScript side (1) is loading the URL
asynchronously and (2) is capable of parsing strings that may or may not
be represented as URL/NSURL.

The Android method loadURLString(String) may have been called
loadURL(String) to overload loadURL(URL) but I didn't want to do that
because:

1. It would not be compatible with existing source code such as
loadURL(null) which would have become ambiguous.

2. I wanted to achieve better convergence with the iOS API.