Order of evaluation for named arguments

[Steven Schveighoffer]

In the D spec, the function parameter [section on order of 
evaluation](https://dlang.org/spec/expression.html#order-calls) 
says:

> Arguments are evaluated left to right.

So a question was raised, what about named arguments, since those 
might not match the order of parameters?

I decided to test:

```d
import std.stdio;
void foo(int a, int b) {
    writeln(i"a: $(a), b: $(b)");
}

void main() {
    int x;
    foo(b: ++x, a: ++x);
}
```

According to the spec, this should print "a: 2, b: 1", as the 
order of evaluation of the expression should go left to right. 
But the actual printout is "a: 1, b: 2".

So the question is, should we modify the spec to reflect this, or 
would it be better to change the compiler to enforce this 
left-to-right evaluation rule?

-Steve