The proper syntax for defining user-defined literals does not require a
space between the `operator""` token and the operator name:
> error: identifier 'sv' preceded by whitespace in a literal operator
> declaration is deprecated
This will make it easier to support both string types at the same time
while we convert code, and tracking down remaining uses.
One big exception is Value::to_string() in LibJS, where the name is
dictated by the ToString AO.
It's not at all obvious how we need three different array-like types.
This change to the Patterns documentation attempts to explain why they
exist, how they differ (mostly in allocation behavior) and what their
use cases are. This builds on #11844 which fixates and tests the
hereby-described allocation behavior of FixedArray.
