There are many cases which shouldn't even parse, like
null = ...
true = ...
false = ...
123 = ...
"foo" = ...
However this *is* valid syntax:
foo() = ...
So we still have to keep the current code doing a runtime check if the
LHS value is a resolvable reference. I believe this was declared valid
syntax to *in theory* allow functions returning references - though in
practice that isn't a thing.
Fixes#2204.
The addition of assert functions to Userland/js
was done before we had load(..) implemented. Now
that it exists, it seems like the right move the
test helper functions to pure javascript instead
of poluting js with random global functions.
